Answer: 13 months
Explanation:
I made these into equations first.
40 (initial fee) + 65x (x is the number of months) = total cost
170 (initial fee) + 55x (x is the number of months) = total cost
There are two ways to go about this.
1. Put it into a graphing calculator (or a site like desmos) and see where the lines intersect (the easiest way)
2. If you don't have access to either of those, do the old guess and check by plugging in numbers of months until you get your desired answer.