The number of trees is three times more than the number of stones in the courtyard. There are also twice as many birds in the trees as the combined number of trees and stones in the yard. If the number of stones is 40, how many birds are in the trees?
How many trees are there? ** The number of trees is three times more than the number of rocks, meaning there are 3*40 = <<3*40=120>>120 more trees than rocks in the courtyard.
How many trees are there? ** The total number of trees in the yard is 120+40 = <<120+40=160>>160
How many trees and stones are there? ** Combined, there are 160+40 = <<160+40=200>>200 trees and stones in the courtyard.
How many birds are in the trees? ** Since the number of birds is twice the combined number of trees and stones in the courtyard, there are 2*200 =<<2*200=400>>400 birds on the trees.
#### 400