How many positive integers less than 20 have exactly two positive divisors

Which system of linear inequalities is represented by the graph?

What is the inverse of the function f(x) = 2x + 1?

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?