a. Cost for Plan A: $20 + $.45(120) + $.20(40) = $82 Cost for Plan B: $20 + $.55(120) + $.15(40) = $92 Cost for Plan C: $20 + $80 + $.40(0) = $100 Plan B b. $140 Plan A $120 Plan C $100 Monthly cost $80 $60 $40 $20 200 300 Minutes of daytime calls (evening minutes ignored)