Please refer base on Malaysian Law

State whether Abu is required by consideration to fulfil his promises in the following situations and explain the reasons for your answer with relevant authorities.

a)Abu promises to sell an expensive car to Rafiq for RM1,000.

b)Abu returns home and finds that Jack had cleaned his house and he promises to pay RM100 for his work.

c)Abu promises to release Ali from debt of RM2,500 if Ali pays him RM1,200 in November 2020.

d)Abu promised to pay his brother RM300 per month until his brother start working, so that Abu's father will transfer his car to Abu name.