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?

The inequality that will determine the number of months, x, that are required for the second phone to be less expensive is
.

The solution to the inequality is
.

Sal’s mother would have to keep the second cell phone plan for at least
months in order for it to be less expensive.

Answer 1

1) 100 + 55x > 150 + 51x

2) x > 12.5

3) 13

Explanation:

Got it right on Edge :D

Answer 2

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

Explanation:

Since Sal is trying to determine which cell phone and service plan to buy for his mother, and the first phone costs $ 100 and $ 55 per month for unlimited usage, while the second phone costs $ 150 and $ 51 per month for unlimited usage, to determine how many months will it take for the second phone to be less expensive than the first phone, the following calculation must be performed:

100 + (55 x 10) = 100 + 550 = 650

150 + (51 x 10) = 150 + 510 = 660

100 + (55 x 12) = 100 + 660 = 760

150 + (51 x 12) = 150 + 612 = 762

100 + (55 x 13) = 100 + 715 = 815

100 + (51 x 13) = 150 + 663 = 813

Therefore, it will take 13 months for the second phone to be less expensive than the first phone.