Answer:
8x
Explanation:
To do this we simply add the coefficients of x to give us our answer:
3 + 5 = 8
So our answer is 8x
One way to put this into perspective is to imagine x is the number of apples:
If you add 3 apples and 5 apples you get 8 apples.
Always do this trick when collecting like terms in algebra.