Answer:
• 0.06x+(800-0.04x)=1000
,• The amount invested at both rates is $10,000.
Explanation:
• Let the amount invested at a 6% rate of return = x
Since the total amount is $20,000
• The amount invested at a 4% rate of return = $(20,000-x)
Interest at 6%
[tex]\begin{gathered} I=x\times0.06\times1 \\ I=0.06x \end{gathered}[/tex]Interest at 4%
[tex]\begin{gathered} I=0.04(20000-x) \\ I=800-0.04x \end{gathered}[/tex]The total return on investment was $ 1000, therefore:
[tex]\text{Total Interest = 0.06x+(800-0.04x)}=1000[/tex]We can then solve for x to determine the amounts invested:
[tex]\begin{gathered} 0.06x-0.04x=1000-800 \\ 0.02x=200 \\ x=\frac{200}{0.02} \\ x=10,000 \end{gathered}[/tex]The amount invested at both rates is $10,000.