Answer:
The graph is a plot of cost of call(in dollars) on the y axis against number of minutes used per month on the x axis
For plan A, the cost of call(in dollars) varies directly with the number of minutes used per month.
For plan B, the cost(in dollars) of call is constant regardless of the number of minutes used per month.
a) From the graph,
50 minutes of long distance call for the month using plan A, costs $4
50 minutes of long distance call for the month using plan B, costs $20
It costs $16 ($20-$4) more to use plan B than to use plan A.
b) the two plans cost the same when the number of minutes is 250. This is the point where both lines coincide.
If the time spent on long distance calls is less than 250 minutes, then plan plan B costs more.
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