Answer:
The amount invested at 9% was $3,200 and the amount invested at 13.5% was $1,800
Step-by-step explanation:
Let
x ----> the amount invested at 9% (first fund)
5,000-x ----> the amount invested at 13.5% (second fund)
Remember that
[tex]9\%=9/100=0.09[/tex]
[tex]13.5\%=13.5/100=0.135[/tex]
The total interest earned is equal to
[tex]\$5,531-\$5,000=\$531[/tex]
we know that
The amount earned by the first fund at 9% plus the amount earned by the second fund at 13.5% must be equal to $531
so
the linear equation that represent this situation is equal to
[tex]0.09x+0.135(5,000-x)=531[/tex]
solve for x
[tex]0.09x+675-0.135x=531[/tex]
[tex]0.135x-0.09x=675-531[/tex]
[tex]0.045x=144[/tex]
[tex]x=\$3,200[/tex]
so
[tex]\$5,000-x=\$5,000-\$3,200=\$1,800[/tex]
therefore
The amount invested at 9% was $3,200 and the amount invested at 13.5% was $1,800