Question

rose wants to have 7,500 in 18 years how much rose should invest now at 8% interest

Answer 1

Use compound interest formula:

Fv=Pv(1+i)^n
here
Fv=7500
Pv=present value to be calculated
i=8%=0.08 (assume compounding annually)
n=18

transposing,
Pv=Fv/(1+i)^n