1. The issue that arises concern the offer made on 1st of January; that is whether Bob would be liable for the offer that he made on the said date. From the stated facts, it is clear that Mike did not in the first instance accept the offer made by Bob, but he in turn made another offer which Bob refused.
The law of contract requires that when an offer is made it should be accepted without any alteration by the accepting party. Therefore if an offeree puts some other conditions which are not reflected under the offer it is deemed that the offer has been rejected. When the offeree changes the terms of the offer then it is deemed that such a party has made a counter offer than can either be accepted or rejected.
It is therefore clear from the above facts that the offer made by Bob on the 1st January was rejected by Mike and he in turn made a counter offer. Bob ordinarily is not obliged to accept the counter offer made by Mike. Therefore Bob owes no responsibility to Mike since the offer he made was rejected by him when he altered the terms of the offer.
The law of contract requires an offer to be accepted without any change of terms by the offeree. A change results in a counter offer hence the first offer would be rendered void. Therefore, there are liabilities or rights in these set of facts between Bob and Mike that can be enforced in a court of law.
2. The issue that is to be determined is whether the offer made on 10th January is enforceable under the law of contract. This, however, would be in light of the prevailing circumstances which would probably give rise to another issue. This issue is whether the email sent to cancel the order would have the effect of vitiating the contract in relation to the letter of acceptance posted prior.
The law of contract requires the offeree to accept the terms of the contract unconditionally. A communication of acceptance can be made through many ways. One of the ways through which acceptance is made is by way of postage of a letter. Generally, it is deemed that acceptance has been made on the day the letter is posted and not on the date of the receipt of the said letter. Therefore the email sent after the postage of the letter of acceptance cannot annul the acceptance made initially by way of postage of letter of acceptance.
The offer made on 10th of January is validly accepted since there is no such alteration made on the face of it. By posting a letter of acceptance on 12th January, it is deemed in the law of contracts that acceptance was made on the 12th January. The email sent to cancel the offer does not supersede the letter of acceptance posted.
Acceptance is made once the letter of acceptance has been posted. The law of contract, therefore, requires Bob to take delivery and pay for the goods delivered since acceptance was made on the 12th January.
3. The issue at hand here is whether the promise made can be enforced under the law of contract. This would be interesting since the promise was not written down.
However, under the law of contract verbal agreements can be enforced. However, they have to be made in good faith and they ought to be reasonable. The person making the promise should demonstrate his commitment to fulfilling the promise that he made. It is important to take cognizance of a consideration made in promises since they would be enforced based on a consideration advanced by the offerer. It is important in verbal contracts to establish whether all the ingredients of a valid contract exist.
In determining the enforceability of a promise, it is important to establish whether there is a consideration or not. The new computer, which is to be given because of favors done to Bob is the consideration in this instance. The contract, therefore, is enforceable since there was a consideration. It is also clear from the facts that Bob was committed and he intended to fulfill his promise. He, in fact, made the promise in good faith.
A promise, therefore, can only be enforced if the promisor intends to fulfill his promise and he in fact makes the promise in good faith. Consideration is a basis in enforcement of any promise made. In this case, Steve can successfully claim the new computer promised since the promise was made in good faith and there is a consideration in place.
4. The issue herein is whether the offer form signed wrongly by Bob without his knowledge of what is contained therein is valid.
The law of contract gives a remedy to instances when fundamental mistake that goes to the root of the contract are occasioned. In court, whenever a party claims that what he signed is fundamentally different to what he believed, a plea of non est factum is pleaded (Petelin v Cullen
High Court of Australia (1975) 132 CLR 355). In essence, the party disputing the offer or contract to which he signed tells the court that it was by mistake and without his knowledge that he signed the alleged document. This plea asserts that the document signed is different from the one intended to be signed (Saunders v Anglia Building Society (Gallie v Lee)  AC 1004).
In this situation, it is clear that Bob never intended to sign the offer presented by Mary. He signed the document thinking it was another contract presented by a microchip company. This is a fundamental mistake that would invite the plea of non est factum to remedy the mistake. The document was fundamentally different from the one he thought he was signing.
Bob in this instance signed a different document that he did not intend to. Ordinarily, if the strict law of contract is enforced, Bob would have to be disadvantaged as a result of a fundamental mistake. The law of contract, however, contemplates such instances and it provides a window to the aggrieved party and hence the contract is held void. Mary therefore in this instance cannot enforce the offer made.
“Chapter Three: The Law Of Contracts”. 2017. https://www.longchamps3e.nelson.com/instructor/03Ch03.pdf.
“Is A Verbal Agreement Legally Binding?”. 2017. Findlaw.Com.Au. https://www.findlaw.com.au/articles/5626/is-a-verbal-agreement-legally-binding.aspx.
Corbin, Arthur L. “Offer and Acceptance, and Some of the Resulting Legal Relations.” The Yale Law Journal 26, no. 3 (1917): 169-206.
Hill, Simone W. B “Email Contracts - When is the Contract Formed?”  JlLawInfoSci 4; (2001) 12(1) Journal of Law, Information and Science 46
Household Fire and Carriage Accident Insurance Co v Grant (1879) 4 EX D 216
Normile v. Miller, 326 S.E.2d 11 (1985).
United Nations Convention on Contracts for the International Sale of Goods citation, 11 April 1980.