John has $6000 to invest. He invests part of it at 5% and the rest at 8%.How much should be invested at each rate to yield 6% on the total amount?

Answer 1

$X @ 5%
$(6000-x) @ 8%

0.05x + 0.08(6000-x) = 0.06*6000
Multiply both sides by 100:
5x + 8(6000-x) = 6*6000
Solve for x.

Answer 2

X=4000