Need someone to explain to me how to solve this, not just give an answer !
john wants to have $2 000 in 3 years. the current rate of return for a high interest savings account is 2.8%, compounded annually. the money, p dollars, that john must invest now is given by the formula p initial investment = 2 000 (1.028) -3, where the exponent of the power is the time, in years.

a. how much must john invest now to have $2 000 in 3 years?

b. assuming the interest rate remains consistent, how much money will john have in 5 years if he doesn’t touch the investment after the initial 3 years?