The annual returns on Sid Carrington's three investments amounted to $9,990: 3% on a savings account, 5% on mutual funds, and 6% on bonds. The amount of Sid's investment in bonds was twice the amount of his investment in the savings account, and the interest earned from his investment in bonds was equal to the dividends he received from his investment in mutual funds.

Find how much money he placed in each type of investment. (Let x, y, and z denote the amount, in dollars, in savings, mutual funds, and bonds, respectively.)