<span>B) Because the car could only seat four people, we had to make two trips.
The comma should only be used after the first predicate !</span>
3x + 7 = x - 15
First, make sure to subtract

from both sides.
Second, simplify 3x - x to get 2x, and then keep the 7.
Third, subtract

from both sides.
Fourth, simplify -15 - 7 to get -22.
Fifth, take the 2 and divide both sides by it, keeping the

by itself.
Sixth, since 11 goes into 2 to get 22, simplify the fraction to 11.

Answer:
x = -11
If you don't have answer choices, I would say either peer editing or reading it aloud and listening for errors.