math
posted by pb .
jack invested $4000 in two accounts. one pays simple interest at the rate of 5% and the other pays simple interest at the rate of 6%. if jack earned a total of $224 in interest in the first year, how much did he invest in each account?

He invested:
$X @ 5%.
$(4000X) @ 6%.
.05x + 0.06(4000x) = 224.
0. 05x  0.06x + 240 = 224.
0.01x = 224  240 = 16.
X = $1600.
4000X = 40001600 = $2400.