He is buying one large tree, so subtract the cost of a large tree from the total:
1400 - 200 = 1200
He can spend 1200 on small trees.
Divide 1200 by the cost of a small tree to find how many small trees can be bought:
1200 / 150 = 8
He can buy 8 small trees.
Total number of trees = 8 small + 1 large = 9 total
