Well..

get both, check their difference, that's how much more tax you'd be paying from 7.5% to 8% on $10
This is not a difficult question and I will help you solve it :)
When calculating 1/10 from 40, what we have to do is this:
(1/10) * 40 = 4
This means that we have to multiply 40 by 1 and divide by 10 :)
So the answer in this case is 4.
The employee receives $162 because you just substitute 6 for h and w for 3 which is 12(6)+30(3) and 12x6=72 and 30x3=90 and 72+90=162