You can set up an inequality to solve this. You can either do big to small --> [tex]\frac{x}{18} = \frac{20}{8}[/tex] or small to big --> [tex]\frac{x}{18} = \frac{8}{20}[/tex]. I'm going to be using big to small because I think it's a little easier.
[tex]\frac{20}{8} = \frac{x}{18}[/tex]
Cross multiply and you will get:
[tex]360 = 8x[/tex]
Isolate x:
[tex]x = \frac{360}{8}[/tex]
x = [tex]\frac{90}{2}[/tex]
x = 45
The goal post is 45 feet tall. Hope this helped. Good luck. : )
