Which ratio is not equivalent to 5:8?

What is the least common factor of 6 and 8

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?

Hi, can anyone show me how to do this problem? 100 points for this. in advance