I am not sure what you mean, but x=4
Answer:

Step-by-step explanation:
How to factor expressions?
Find the G.C.F. and divide it into the terms of the expression you need to factor, like this:
. So I took the 12 and pulled it out of both terms, obtaining
.
Answer:
37.5
Step-by-step explanation:
so x% of 40 is 15
the equation for that is
x/100 * 40 = 15
40x/100 = 15
multiply 100 on both sides
40x = 1500
divide 40 on both sides
37.5
37.5% of 40 is 15