Has to be answered in the IRAC method

1.Delilah makes a written offer to Samson to sell her mountain bike for $1000. In her offer Delilah states, that 'this offer will remain open for seven days'. Two days later Delilah tells Samson that she has changed her mind.

a)Discuss whether under common law Samson can still accept the offer and hold Delilah to the sale of her mountain bike to him for $1000.

2.Catherine promised her 19-year-old son, Lawrence that if he refrained from smoking until he was 21, that she would buy him a BMW. Lawrence has been refraining from smoking. Lawrence has just turned 21 but Catherine refuses to buy the BMW, saying that Lawrence not smoking has been good for his finances as he has some savings and more importantly his health.

a)Does Lawrence have a valid claim against Catherine to make her buy him the promised BMW? Why, and why not?

[HINT - consideration]