Question

A tree casts a shadow that is 8 feet long, a 3 foot mailbox cast a shadow that is 5 feet long. how tall is the tree?

Answer 1

Set up two fractions:
8/x and 3/5
Set them equal to each other and cross multiply to get:
8*5 = 3x
40 = 3x
13.3 = x or 13 and 1/3 feet tall.