Hi Sean

Check the definition of Simple Interest

I = Prt

Remember to write the rate as a decimal

I = Money earned over time on the investment

P =Principal the starting amount of the investment

r = interest rate per year

t = time in years

For you data P=$700; r=9%; t=4 years; I=? just plug it in

You want to look up these formulas to make sure you are using the correct one, for your class