Answer:
the first and second car seats are appropriate for a 33 lb. child. The first seat suits children up to 34 lb. The second seat suits children that weight between 16 to 40 lb.
The only seat that is not appropriate would be the third one that is too large, since children between 34 to 90 lb. should use it.
seat 1 ≤ 34 lb ⇒ simple inequality
16 lb < seat 2 and seat 2 < 40 lb ⇒ compound inequality
34 lb < seat 3 and seat 3 ≤ 90 lb ⇒ compound inequality