Revenue Equation. A small business predicts its revenue growth by a straight-line method with a slope of $60,000 per year. In its fifth year, it had revenues of $400,000. Find a function that describes the relationship between revenues R and the number of years T since it opened for business. Appreciation. A house purchased for 240,000 is expected to double in value in 12 years. Find a linear equation the describes the house's value after tyear. Photo