Study the scenarios

Refer to https://en.wikipedia.org/wiki/Contract.

Scenario 1: Joe and George are good friends. Joe is a Builder and George is in Underwear. George wants a house built so after a few drinks Joe says, "You get the materials and I will build it for you". George accepts Joe's offer, they shake hands and seal the offer with another round of drinks. When George buys the materials he cannot get Joe to build because Joe is too busy on another contract.

a)What is the legal position?

Scenario 2: George has plans prepared for a house. Joe offers to build the house for $50,000. George agrees to have Joe build, it if he can do it for $45,000. With no further communication Joe builds, and invoices the full $50,000 saying he had never agreed to any subsequent figure.

b)What is the legal position?

Scenario 3: Party A advertises a car for sale for $10,000. Party B has a look at the car and says, "Looks OK but your asking price is too high for me, I'm offering you $8,000." Party A says, "I'll be in touch if I don't get a better price." The next day Party A rings Party B and says, "Your price was the best, I'll take it". Party B says, "Sorry, I bought another car this morning."

What is the legal position?