Please i need help with this

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?

What is the common difference for this arithmetic sequence? -6,-2,2,6,10 a.4 b.5 c.3 d.6

According to the general equation for conditional probability if p(anb)=3/7 and p(b)=7/8 what is p(a i b)