A cell phone plan is shown at the right. The rates
, which include an unlimited data plan, are the
same each month for 7 months. The total cost for all 7 months
is 180.39. Let m represent the average number of minutes that
exceeds 700 minutes each month,
a. Write an equation to represent the given situation.
b. Solve the equation to determine how many additional
minutes, on average, you use each month.