Step-by-step explanation:
I think c is right answer
Let
T---------> <span>the tax rate on the parts in $
we know that
$18.75=$15+$3.50+$T
T=18.75-15-3.5
T=$0.25
so
$3.50----------> 100%
$0.25--------> x
x=0.25*100/3.50------> x=7.14%------> x=7.1%
the answer is
7.1%</span>
