Answer true or false to each statement, and explain your answers.

a. The graph of a linear equation slopes upward unless the slope is 0.

b. The value of the y-intercept has no effect on the direction that the graph of a linear equation slopes.

4.23 Rental-Car Costs. During one month, the Avis Rent-A-Car rate for renting a Buick LeSabre in Mobile, Alabama, was $68.22 per day plus 25c/ per mile. For a 1-day rental, let x denote the number of miles driven and let y denote the total cost, in dollars.

a. Find the equation that expresses y in terms of x.

b. Determine b0 and b1.

c. Construct a table similar to Table 14.1 on page 642 for the x-values 50, 100, and 250 miles.

d. Draw the graph of the equation that you determined in part

(a) by plotting the points from part

(c) and connecting them with a line.

e. Apply the graph from part

(d) to estimate visually the cost of driving the car 150 miles. Then calculate that cost exactly by using the equation from part (a).