Question

Regina Smith earned $84 in simple interest in 8 months at an annual interest rate of 3%. How much was her initial investment? (Hint: Use the formula I = prt and substitute known values to find I.)

So I got P*(0.03*8/12) = 84 and can't find p pls help

Answer 1

I = PRT.....but we are looking for p, so rearrange...
I / RT = P

R = 3% = 0.03
T = 8/12
I = 84

84 / (0.03 * 8/12) = P
84 / (0.24/12) = P
84 / 0.02 = P
4200 = P

check..
I = PRT
84 = (4200)(0.03)(8/12)
84 = 126(8/12)
84 = 1008/12
84 = 84....correct

so the principal is : $ 4200