Answer:
7 minutes
Explanation:
Antonio's plan: Monthly cost
3 (.75m + 10) + 2.50m – 15
Marcus's Plan: Monthly cost
2 (1.75m + 12.50) – .75m + 4
where, m = number of minutes used by setting their monthly cost equal
3 (.75m + 10) + 2.50m – 15 = 2 (1.75m + 12.50) – .75m + 4
2.25m + 30 + 2.50m - 15 = 3.5m + 25 - .75m + 4
4.75m + 15 = 2.75m + 29
4.75m - 2.75m = 29 - 15
2m = 14
Divide both sides by 2
m = 14 / 2
= 7
m = 7 minutes