Jerry had 36 action figures on a shelf in his room. Later he added 42 more action figures to the shelf and removed some of the old ones. If there are 24 action figures on his shelf now How many action figures did he remove from the shelf?
Jerry had 36 action figures on a shelf in his room. 

This is our starting point, and we know that the answer is not 36. 

Later he added 42 more action figures to the shelf and removed some of the old ones. 

We're told that Jerry added 42 action figures to the shelf, and that he removed some old ones. We don't know how many he removed, but we know the answer is not 42. 

If there are 24 action figures on his shelf now

We're told that there are 24 action figures on Jerry's shelf now. 

How many action figures did he remove from the shelf?

This is what we're trying to figure out. We know that Jerry started with 36 action figures, added 42, and that there are 24 on the shelf now. So, we can say that Jerry removed ____ action figures from the shelf.