A trainer for a professional football team keeps track of the amount of water players consume throughout practice. The trainer observes that the amount of water consumed is a linear function of the temperature on a given day. The trainer finds that when it is 90 degrees the players consume about 220 gal. of water, and when its 76 degrees the players consume about 178 gallons of water.

Write a linear function to model the relationship between the gallons of water consumed and the temperature.

The slope for the function graph is (220 - 178)/(90 - 76) = 42/14 = 3. Use the point-slope form of the linear equation: y - 178 = 3(x - 76) or y = 3x - 228 + 178 = 3x - 50.

The slope is the rate of change of the water consumed with the temperature. In fact, when the temperature rises by 1 degree the players consume extra 3 gallons of water during their practice.