How much did he invest in each account?

Question

Last year, Ali had $30,000 to invest. He invested some of it in an account that paid 5% simple interest per year, and he invested the rest in an account that paid 7% simple interest per year. After one year, he received a total of $1740 in interest. How much did he invest in each account?

First Account: $____

Second Account: $____

Answer 1

.04x + .07(30,000-x) = 1740

-.03x = 1740 -2100 = -360

x = 360/.03 = $12,000 invested at 7%

30000-x = $18000 invested at 4%

.04(12K) +.07(18K) = .48K +1.26K = 1.74K = $1,740

1740/30000 = 174/3000 = 58/1000 = 5.8%

7-5.8 = 1.2, 5.8-4 = 1.8

18/12 = 3/2 = 18000/12000 = 18/12 = 3/2 times as much invested at 7% as 4%