Last year, Juan had $30,000 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 9% simple interest per year. After one year, he received a total of $2320 in interest. How much did he invest in each account?

Question

Nathalia Lynch

Mathematics

7 June, 11:03

Last year, Juan had $30,000 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 9% simple interest per year. After one year, he received a total of $2320 in interest. How much did he invest in each account?

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Answers (1)

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Dangelo Moran · Answer 1

Let x be the amount invested at 7%, leaving 30000-x to be invested at 9%.

The equation is

2320 = 0.07 x + 0.09 (30000 - x)

2320 = - 0.02 x +.09 (30000)

0.02 x =.09 (30000) - 2320

x = (.09 (30000) - 2320) /.02

x = 19000

Answer: $19000 at 7%, $11000 at 9%

Check:

19000 (.07) + 11000 (.09) = 2320, good