Simplifying an expression
In order to simplify an expression, we add or substract similar terms with each other: terms with x on one hand, numbers on the other.
Then, in this case
12x - 3x - 10 + 2x - 2
terms with x are: 12x, -3x and 2x
numbers are: -10 and -2
We add them:
12x - 3x + 2x = 11x
-10 - 2 = -12
Then
12x - 3x - 10 + 2x - 2 = 11x - 12
Answer: 11x - 12