Answer: the amount of money invested at the rate of 8% is $9000
the amount of money invested at the rate of 6%. Is $12000
Explanation:
Let x represent the amount of money invested at the rate of 8%.
Let y represent the amount of money invested at the rate of 6%.
Mr. May invested $21,000, part at 8% and the rest at 6%. This means that
x + y = 21000
The formula for simple interest is expressed as
I = PRT/100
Where
P represents the principal
R represents interest rate
T represents time
Considering the investment at the rate of 8%,
P = x
R = 8
T = 1
I = (x × 8 × 1)/100 = 0.08x
Considering the investment at the rate of 6%,
P = y
R = 8
T = 1
I = (y × 8 × 1)/100 = 0.06y
If the annual income from both investments were equal, it means that
0.08x =0.06y - - - - - -1
Substituting x = 21000 - y into equation 1, it becomes
0.08(21000 - y)=0.06y
1680 - 0.08y = 0.06y
0.06y + 0.08y = 1680
0.14y = 1680
y = 1680/0.14 = 12000
Substituting y = 12000 into
x = 21000 - y
x = 21000 - 12000
x = 9000