Alex is x years old. Addison is y years younger. Find their combined age in 10 years’ time.

x+10-y

Step-by-step explanation:

i'm not 100% sure about this response, but i'd assume the answer is like this for the following reasons:

alex is x years old, and 10 years have passed, meaning 10 years are added onto his age (x+10). addison is still the same amount of years apart from him in age, so you subtract y from that (x+10-y).