If 9 is less than 3 times a certain number is 15 find the number. Please answer

What is the order of magnitude for the number of liters in a large bottle of soda served at a party

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?

With alll of except for the 2 that i did already