Modeling
Using Linear Systems
Example
Anne is trying to choose between two phone plans. The first plan, with Vendafone costs $20 per month, with calls costing an additional 25 cents per minute. The second company, Sellnet, charges $40 per month, but calls cost only 8 cents per minute. Which should she choose?
Step 1. Write an equation for each plan.
y = total cost of the plan and x = number of minutes
Vendafone: y = 0.25x + 20
Sellnet: y = 0.08x + 40
Step 2. Solve the system of equations using one of the methods discussed earlier.
The following is a graph representing the situation.
The intersection point is (117.65, 49.41)