I need help with this three problems (with procedure)

Trish receives $450 on the first of each month. josh receives $450 on the last day of each month. both trish and josh will receive payments for next four years. at a discount rate of 9.5 percent, what is the difference in the present value of these two sets of payments?

Can any one me with the answers to these questions asap?

Ateacher noticed 5/8 of the students were wearing either blue shorts or white shorts. write two different ways this could be done.