As per the problem
A tree farmer planted 3 types of trees on 22 acres of land.
Farmer planted 48 trees per acre.
It mean that farmer has planted 48 trees in 1 acre.
Total number of trees planted can be found by multiplying number of trees in 1 acre by total number of acre.
So the total number of Tree planted in 22 acre

Hence the total number of trees planted in 22 acre is 1056.