Step-by-step explanation:
for #1 it would be the second one.
For #2, it would be the first one
Like terms are the ones that have the SAME variable with SAME exponent. So the ones with x will be considered like terms. The ones with a will also be like terms.
For #1, you would use this fact to combine the like terms. For instance, 3a and -2a are like terms so when they are combined you are left with 1a
