[x = amount earning 6% annually.] (8000-x) = amount earning 15% annually Then we set up our equation which is a sum of the 15% return and the 6% return and we let that sum equal our desired return on investment ($930). Then solve for x. (8000-x)*.15 + x*.06 = 930 1200 - .15x + .06x = 930 .09x = 270 x = 3000. Therefore, you should invest $3000 at 6% and $5000 at 15% to earn $930 annually.
