Last year, Dan had $30,000 to invest. He invested some of it in an account that paid 10% 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 $2,280 in interest. How much did he invest in each account?

Answer 1

Let x be the amount Dan invested in the account that paid 10% interest, and 30,000-x be the amount he invested in the account that paid 7% interest.

The total interest earned from the two accounts is the sum of the interests earned from each account:
0.10x + 0.07(30,000-x) = 2,280
0.10x + 2,100 - 0.07x = 2,280
0.03x = 180
x = 6,000

Dan invested $6,000 in the account that paid 10% interest, and $24,000 in the account that paid 7% interest.