The power company 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. another month, the customer used 1420 kwh and the bill was $120. use the two given points to find the linear equation that models the electric bill (y) in terms of the number of kilowatt hours used (x)