3.the of sets is the set of all the members of both sets without repeating any of the members in the sets.
4.the of two sets is the set of all members that are common to both sets.

my guess is

step-by-step explanation:

well if he bought them at 5 cedis each sold them at 7 cedis each then he would make a profit of 2 cedis of each book. if in total he made 150 cedis profit that means he sold 75 books. he lost 12 books at the start so that means he originally bought a total of 82 books.

step-by-step explanation:

there were a lot of them but the first one to pop up on a google search was bts