Austin can choose Plan A or Plan B for his long distance charges. For each plan, cost (in dollars) depends on minutes used (per month) as shown below. 28 Plan A 26 24- 22- Cost 20- (in dollars) 16- 14- 12- 10- E " " 2 0 0 100 1201010 Minutes used (per month) Plan B (a) If Austin makes 80 minutes of long distance calls for the month, which plan costs less? OPlan A O Plan B How much less does it cost than the other plan? S (b) For what number of long distance minutes do the two plans cost the same? If the time spent on long distance calls is less than this amount, which plan costs less? O Plan A OPlan B X ?