Proportions are also a valuable tool in business. If the time it takes to do a task is directly related to the cost the business has to charge for that task, any task can be evaluated for the cost. Set up a proportion and solve it to demonstrate this type of business application. (An example might be 5 hours / $20 = 10 hours / x). Remember that setting the cross products (multiplications) equal, and then solving for x is the way to solve a proportion.