Gretchen withdrew $31.45 from the bank to buy groceries. then she deposited a check for $27.89 in the bank. which expression represents the net change in her account balance as a result of these two transactions? what is the net change in her account balance?

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?