Answer:
5 cm
Step-by-step explanation:

5 cherry trees and 4 weeping willows?
324 (oil paintings) + 227 (watercolor paintings) = 551
You need to know how many more oil and watercolor paintings there are than statues so you take those 158 statues from 551 oil and watercolor paintings:
551-158= 393 --> there are 393 more oil and watercolor paintings than statues in the museum