Algebra word problem help needed

Question

The simple interest earned by a certain amount of money varies jointly as the
rate of interest and the time (in years) that the money is invested. If $140 is
earned for the money invested at 7% for 5 years, how much is earned if the same
amount is invested at 8% for 3 years?

 

Thanks so much for your help! 

Answer 1

Hey S B.!

So since this is a simple interest problem here is the formula we'll be working with:

I=PRT, where I is the interest earned, P is the investment, R is the interest rate and T is time.

We have two steps.

1) Find P given I, R, T.

$140 = (P)(7%)(5) =$400

2) Find I given P, R, T.

I= ($400)(8%)(3) =$96

Hope this helped!

-Sharmane