Cell phone Plan A costs $80 per month and comes with a free $630 phone. Cell phone Plan B costs $45 per month but does not come with a phone. If you buy the $630 phone and choose Plan B, how many months is it until your cost is the same as Plan A's? Be sure to:
a) Write an equation to represent the situation where x represents the number of months.
b) Show your work to solve the equation from part a using inverse operations.
c) State the answer.