This is a first for me, not very computer literate. Have been out of the business for 8 years due to being disabled. I want to catch up on the technology and to refresh old skills, so please bare with me.

A friend ask me if he had enough return air and it caught me off guard. What do you think?

He has a 4 ton matched system, 20x25 unit opening. His r/a grilles are as follows. 10x36, 10x24. he also has a 20x24 grille blocked off. My question is, is the first two sizes adequate without the 20x24 opening?