Hello Rebekah,

Only the coefficients will change in value.

here, just add the coefficients, of the same variable, taking into consideration the sign also.

the coefficients are -1 and +12; when we add those two , we get +11

Let me give you another example.

Simplify (-5x+8y+12x-19y)

we have two variables here x and y

first take the coefficients of x; -5 and +12. Adding them will give you +7

Noy coefficients of y; +8 and -19. Adding them will give you -11

so the resulting expression will be 7x-11y

Hope this helps.

When combining like terms, first start with the terms without a number in front of it (such as v or -v)  Assume those terms are equal to 1 (so v= 1*v and -v = -1*v)

You can combine -v + 12v = -1v + 12v = v *(-1+12)= 11v

Terms with equal exponents can be combined.  So v can only be combined with v.  v^2 can only be combined with v^2 and so on...

Combine like terms are numbers that are alike, for example: your problem, as you can see v is a variable, and it represents a one, although we don't write it down. 12v is a term that contains a number(coefficient) followed by the variable "v". Therefore, we can combine them. In this case one term is negative and the other term is positive, so you SUBTRACT and keep the sign of the BIGGER COEFFICIENT, which is 12. Your answer is  11v     

           -v+12v= 11v