Problema Solution
melissa invested a sum of money at 3% annual simple interest.she invested three times that sum at 5% annual simple interest.if her total yearly interest from both investments was $7200, how much was invested at 3%
Answer provided by our tutors
let the initial investment be x
then her interest from 1st at 3%investment is 3x/100
then she invested 3 times , so her investment is 3x
therefore, her interest from 2nd at 5% investment is 15x/100
her total interest gained is 7200
therefore, 3x/100+15x/100=7200
x=720000/18
=40000