Acell phone company offers two talk and text plans. the company charges a monthly service fee of $20 for
either plan the customer chooses: customers that choose talk and text plan a are charged five cents a minute
and twenty dollars for 250 texts. customers that choose talk and text plan b are charged ten cents a minute
(first 100 minutes free) and fifteen dollars for 200 texts. the equation: c = .10(m - 100) + 15 + 20 can be used
to represent how much a customer would spend monthly for the minutes used. how many minutes must a
customer use for the cost of the plans to be the same?