Let us assume that total number of trees in the orchard are x.
So,
the lemon trees will be (18)∗x=x8
the mango trees will be (13)∗x=x3
The remaining trees are the banana trees.
Banana trees =x−(x8)−(x3)=(1324)∗x
we are given that banana trees = 117
Banana Trees are
(1324)∗x=117
x=(117∗24)13
therefore, x = 216
Hence, the total number of trees are 216.