Answer:
He can plant 10 trees in 2 hours.
Explanation:
First you need to find the number of trees he can plant in an hour.
For this purpose, we will divide 40 by 8 to get an idea about how many he can plant in an hour.
Trees planted in an hour = 40/8 = 5
Now for 2 hours = 5*2 = 10 trees.