Question 1023874
Call what he invested at 7%, x.  Then what he invested at 3% was 20000-x.  The setup looks like this:
.07x + .03(20000-x) = 1040
.07x + 600 - .03x = 1040
.04x + 600 = 1040
.04x = 440
x = $11000 at 7% and thus
20000-x = $9000 at 3%