Answer:
4 months
Explanation:
Let
x = number of months
Double Mint Mobile = 100 + 30x
BT&T = 20 + 50x
After how many months will both cell phone plans cost the same?
Equate the cost of both phone plans
Double Mint Mobile = BT&T
100 + 30x = 20 + 50x
100 - 20 = 50x - 30x
80 = 20x
x = 80/20
x = 4 months
Number of months = 4 months