Answer:
An algebraic expression to describe the combined number of post for Ashley and Roberto after d days is:
38 d
Explanation:
Ashley post 17 status updates on her wall each day
and Roberto post 21 status updates on his wall each day.
So, combine post of Ashley and Roberto each day is:
17+21=38
So, combine post of Ashley and Roberto after d days is: 38 d
Hence, an algebraic expression to describe the combined number of post for Ashley and Roberto after d days is:
38 d