Cell phone plan A cost 70 a month and comes with a free 500$ phone. Plan B costs 50$ per month but does not come with a phone. If you buy the 500$ phone and choose plan B, how many months is it until your cost is the same as plan A?

Answer: it will take 25 months until your cost is the same as plan A.

Step-by-step explanation:

Let x represent the number of months until your cost is the same as plan A.

Cell phone plan A cost 70 a month and comes with a free 500$ phone. This means that the total cost of using plan A for x months would be

70 * x = 70x

Plan B costs 50$ per month but does not come with a phone. If you buy the 500$ phone and choose plan B, it means that the total cost of using plan B for x months would be

50x + 500

Therefore, for the costs to be the same,

70x = 50x + 500

70x - 50x = 500

20x = 500

x = 500/20

x = 25