## Elementary Algebra

Let X represent the amount invested at 4%. The remainder, which is 2300 - X, will be invested at 6%. From the first investment we earn 4% $\times$ X = 0.04X. From the second investment we earn .06 $\times$ (2300 - X) = 138 - 0.06X. We know that the interest earned by the 6% investment is 50 dollars more than the interest earned by the 4% investment, so we set up the following equation: 0.04X = 138 - 0.06X - 50 0.04X = 88 - 0.06X 0.1X = 88 Divide both sides by 0.1: X = 880 We invested 880 dollars at 4% interest. We invested 2300 - 880 = 1420 dollars at 6% interest.