A basic cellphone plan costs $20 per month for 60 calling minutes. Additional time costs
Chapter 6, Problem 93(choose chapter or problem)
A basic cellphone plan costs $20 per month for 60 callingminutes. Additional time costs $0.40 per minute. The formula
C = 20 + 0.40(x - 60)
gives the monthly cost for this plan, C, for x calling minutes,
where x > 60. How many calling minutes are possible for a
monthly cost of at least $28 and at most $40?
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