The relationship between altitude and the boiling point of a liquid is linear. At sea​ level, the liquid boils at 216 °F. As the altitude​ increases, the boiling temperature of the liquid​ decreases, such that at an altitude of 4,500 ​ft, the liquid boils at 210.15 °F.
Write an equation giving the boiling point b of the​ liquid, in degrees​ Fahrenheit, in terms of altitude​ a, in feet.