Olivia Thoms sells surplus books to bookstores. She is paid a weekly commission of $1.50 each on the first 50 books she sells, $1.75 each on the
next 100 books, and $2 on any books she sells over 150. Last week she sold 225 books.
What was her commission for the week?

Aclassroom is made up of 11 boys and 14 girls. the teacher has four main classroom responsibilities that she wants to hand out to four different students (one for each of the four students). if the teacher chooses 4 of the students at random, then what is the probability that the four students chosen to complete the responsibilities will be all boys?