Question

In how many months will the total cost of both options be the same? What will that cost be?

Answer 1

If you make yourself a monthly expense chart:
Months
1 2 3 4 5 6 7 8 9 10
Opt 1 -80 -30 -30 -30 -30 -30 -30 -30 -30 -30
Opt 2 -40 -40 -40 -40 -40 -40 -40 -40 -40 -40

By month 5 the total amount spent for Opt 1 is $200 and Opt 2 is $200

For part two add up the values for each all the way up to month 9.
Option 1: 80 + 30(8) = 80 + 240 = 320 spent
Option 2: 40(9) = 360 spent

So option 1 is cheaper by month 9