a) The x-axis represents minutes used per month. The y-axis represents cost in dollars. Following the line of the graph indicating 60 minutes per month it shows Plan A costs $6 per month while Plan B costs $12 per month.
Plan A is cheaper.
Difference in prices = cost of Plan B for 60 minutes per month - cost of Plan A for 60 minutes per month
= 12 - 6 = $6 per month
b) To solve, identify where the lines of Plan A and Plan B intersect. Both lines intersect at 160 minutes per month.
Which plan costs less when less minutes are used? To solve, identify which line has a lower cost on the y-axis. Plan A costs less if less than 160 minutes are used.