Solve the equation for x
25-3x=40

X=-5

explanation:
you have to do inverse operation, so subtract 25 and -25 and then on the other side you do 40-25, which equals 15. After that you get -3x=15 and divide -3 on both sides.

The answer will be -5
What ever you do to one side you do to the other

First subtract 25 from itself and do the same to the total
25-3x=40 -3x=15

Next divide -3 from itself and the total ( keep in mind that when you multiply or divide a negative by a positive the answer will be a negative)
-3x=15 X=-5

Substitute 4 for a.

2(4) + 72.6 - (4)
(8) + 72.6 - 4
=76.6

Answer would be 76.6