7x + 15 - 9x = 5 plz help

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?

Can someone tell me if this is perpendicular? !

You borrow $25,000 to buy a boat. the simple interest rate is 4%. you pay the loan off after 10 years. what is the total amount you paid for the loan?