Many of the following problems can be modeled with a linear equation. Analyze them a...

Many of the following problems can be modeled with a linear equation. Analyze them and identify what quantities the variables x and y represent. The information provided in the problems is adequate to determine a point and a slope or two points on the line.

(See Example 14) Valley Electric Utility computes the monthly electric bill for residential customers with a linear function of the number of kilowatt hours (kWh) used. One month, a customer used 1170 kWh, and the bill was $100.02. Another month, the bill was $120.27 for 1420 kWh used.

(a) Does the information provided give two points or a point and a slope?

(b) Find the equation relating kWh used and the monthly bill.