I do not get this question

Find the number of liters in 12.8 gal of gasoline. round to the nearest hundredths

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?

8. kelly wants to buy a magazine that is $25. later the magazine was marked up an additional 20%. what is the new price?