Answer:
a) The tables for both plans are attached.
b) The graph of both plans are attached.
c) If Gertrude is going to make less than 100 calls per month the best plan is Global Cellular. On the other hand, if Gertrude is going to make more than 100 calls per month the best option is Super Cell.
Explanation:
a) We make a table for both companies. You can see that making 100 calls is the same cost per month in both companies.
Super Cell: M(100)=0.15×100+10= $25
Global Cellular: M(100)=0.25×100= $25
b)In the picture attached is shown the graph of both companies. The red line shows the graph of Super Cell plan and the blue line shows the graph of Global Cellular plan.
c) If Gertrude is going to make less than 100 calls per month the best plan is Global Cellular. Because blue line is below the red one(that means Super Cell is cheaper)
On the other hand, if Gertrude is going to make more than 100 calls per month the best option is Super Cell. Because red line is below the blue one(that means Global Cellular is cheaper)