Example of Shadow Problem

A 12 foot tall lamp_post casts an 8 foot shadow at the same time that a tree nearby casts a 28 foot shadow. How tall is the tree?

Find tall

Let S=SHADOW

Let T=TALL

Let s=shadow

Let t=tall

Given S/T=s/t

Given T=12

Given S=8

Given s=28

8/12=28/t Comment: Expand parentheses

8t=12*28 Comment: Simplify

t=42 Comment: Simplify

End

Note that the program used upper case characters for one shadow/height pair, and lower case for the other.