So,
All you have to do is find the total labor cost and put it over the revenue.
We have two workers each earning $8/hr. (lousy), and they work 40 hrs./week.
2 * $8 = $16/hr.
$16/hr. * 40 hrs. = $640

Cross out zeros.

Simplify.



Convert the denominator to 100.


=
32%
The labor cost is 32% of the revenue.