Answer
$8\%$, $116,000$; $18\%$, $4000$ dollars.
Work Step by Step
a. Assume the loan amount for the $8\%$ is $x$ and for the $18\%$ is $y$ dollars. We have $x+y=120,000$ and the total interest is
$I=0.08x+0.18y=0.08x+0.18(120,000-x)=21,600-0.1x$
b. Let $I=10,000$. We have $21,600-0.1x=10,000$. Thus $x=116,000$ and $y=4000$ dollars.
