Select the angle that correctly completes the law of cosines for this triangle. 7^2+25^2-2(7)(25)cos__=24^2

Suppose that a households monthly water bill (in dollars) is a linear function of the amount of water the household uses (in hundreds of cubic feet, hcf). when graphed, the function gives a line with slope of 1.65. if the monthly cost for 13 hcf is $46.10 what is the monthly cost for 19 hcf?