Answer:
It will take 13 months for the second phone to be less expensive than the first phone.
Step-by-step 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.
