Pulling an Equation out of a Word Problem
The cost of water use (in dollars) is a linear function of the amount of water used (in hundreds of cubic feet, HCF), as shown in the figure below. The cost for using 19 HCF of water is 33.75 , and the cost for using 36 HCF is 61.80 . What is the cost for using 34 HCF of water?