Thirteen trees were planted in one row at a distance of three meters from each other.

Thirteen trees were planted in one row at a distance of three meters from each other. Find the distance between the outermost trees.

If there are 13 trees and they are planted in one row, then there will be 12 total distances between them, since the number of distances is the number of objects minus 1.
In total, we got 12 distances and one is equal to 3 meters, that is, 3 must be multiplied by 12:
3 * 12 = 36 meters – the distance between the first and the last tree.
Answer: The distance between the outermost trees is 36 meters.