What is the reciprocal of 4/15

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?

Let f(x) = 5/x and g(x)=2x2+5x. what two numbers are not in the domain of f o g

Which expression is equal to (f+g)(x)?