Image source: http://www.njpsa.org/graphics/catering.jpg
The cross-product property can be used to find unknown amounts in a proportion.
For example, the catering business produces food in large quantities. If a recipe
that serves 5 requires 2 pounds of beef, then a recipe that serves 180 should
require 72 pounds of beef. You can find this answer using the proportion 2/5
= x/180. Using the cross-product property will help you simplify this equation
to 360=5x. Then, after dividing both sides by 5, you end up with x = 72.