(1) Analysis: Because it is impossible to plant trees against the wall, it belongs to the case of planting trees at two ends, and the formula is:

Number of trees = number of segments divided-1 (this is the case of planting trees on one side, and planting trees on both sides is better than planting trees on the other side)

(2) How many trees should be planted in a * * *

: (160/4)- 1*2=78 trees