Question

Last year, Abdul had $10,000 to invest. He invested some of it in an account that paid 7% simple interest per year, and he invested the rest in an account that paid 10% simple interest per year. After one year, he received a total of $970 in interest. How much did he invest in each account?

Answer 1

$10,000
→ some 7% simple interest / year
→ some 10% /year
1yr =$970
17% (which is the sum of both simple interests 10% + 7%) = $ 910

Now I’m solving this just as you would with ratio

If 17% of simple interest is equal to $970…
What about 10% of the interest?

Cross multiply here
10% × $970 = $9700

$9700 divided by 17% = $570.588

$970 (total interest) - $570.588 (10% of the interest) = The remaining part of the interest which is 7%

7% = $ 399.412
10% = 570.588