Question

Sal is trying to determine which cell phone and service plan to buy for his mother. The first phone costs $100 and $55 per month for unlimited usage. The second phone costs $150 and $51 per month for unlimited usage. How many months will it take for the second phone to be less expensive than the first phone?

Answer 1

Answer:

It takes 13 months for the second phone to be less expensive than the first phone.

Step-by-step explanation:

First phone: y = 100 + 55x

Second phone: y = 150 + 51x

(x = number of months, y = total cost)

Make a T-Chart.

First phone:                   Second phone:

 x  |   y                                   x  |   y  

0  |  100                                 0  |  150

1   |  155                                 1   |  201

2  |  210                                 2  |  252

3  |  265                                3  |  303

4  |  320                                4  |  354

5  |  375                                5  |  405

6  |  430                                6  |  456

7  |  485                                7   |  507

9  |  595                                9  |  609

10  |  650                               10 |  660

11   |  705                               11   |  711

12  |  760                               12  |  762

13  |  815                                13  |  813

After 13 months, the second phone will have costed $2 less than the first phone, and the price of the second will continue to be lower than the first.