Simply this expression. Which like terms can she combine 12-4x+3

like terms include terms that you can add/sub/mult/div - certain terms ...

for example 23 and 7 are like terms, 4x and 56x are like terms ...

here-> 12 and 3 are like terms so you can put them together:

12 + 3 - 4x

then you can simplify it:

15 - 4x is your answer (most simplified)