Let's say you own a silk screening business in which you print t-shirts. The cost of printing the t-shirts would be $2 per t-shirt in this particular year plus the cost of ink for the year which is a flat rate of $500. The cost equation for this business would be:
C = 500 + 2x where x represents the number of t-shirts printed
Let's say that the t-shirts are sold to customers at a price of $5 per t-shirt. The revenue equation of the business would be:
R = 5x where x represents the number of t-shirts sold or the number of customers who bought a t-shirt.