Question

An executive invests $24,000, some at 6% and some at 4% annual interest. If he receives an annual return of $1320, how much is invested at each rate?

Answer 1

Let x=Amount invested at 6%
Let y=Amount invested at 4%

x+y=24,000
0.06x+0.04y=1320 Solve these equations by multiplying the top one by 0.06 to eliminate x and find y:

0.06x+0.06y=1440
0.06x+0.04y=1320 Subtract this equation from the top one to get:

0.02y=120
y=$6000 invested at 4% Substitute 6000 into x+y=24,000 to find x:

x+y=24,000
x+6000=24,000
x=24,000-6000
x=$18,000 invested at 6%

Therefore, $6000 is invested at 4% and $18,000 is invested at 6%