Question

You charge customers $18.75 for lube service, parts, and labor. Assuming you take one hour's labor at $15, and the parts cost $3.50, what is the tax rate on the parts?
To the nearest tenth ?%.

Answer 1

Let
T---------> 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%