Mr. Lee took the $1200 he collected fr chinese new yea and invested some in a 6% bond, and the rest at a 4.5% T-bill. The return for the T-bill exceeded thay from the bond by $12. How much was invested at each rate?
amount invested at 6% --- x
amount invested at 4.5% --- 1200-x
.045(1200-x) - .06x = 12
54 - .045x - .06x = 12
-.105x = -42
x = 400
so $400 at 6% and $800 at 4.5%