please help

A real estate agent is considering changing her land line phone plan. There are three plans to choose from, all of which involve a monthly service charge of $20. Plan A has a cost of $.44 a minute for daytime calls and $19 a minute for evering calls. Plin B has a charge of $54 a minute for daytime calls and $15 a minute for evening calls, Plan C has a flat rate of $80 with 225 minutes of calls allowed per month and a charge of $.40 per minute beyond that, day or evening a. Determine the total charge under each plan for this case: 130 minutes of day calls and 50 minutes of evening calls in a month. (Do not round intermediate calculations. Round your answer to 2 decimal places.) b. If the agent will only use the service for daytime calls, over what raoge of call minutes wa each plan be optimal? (Round eoch onswer to the nearest whole number. Include the indifference point itself in each answer.) c. Suppose that the agent expects both daytime and evening calis. At what point ile. percentoge of total call minutes used for onytime c. Suplis) would she be indifferent between plans A and 8 ? (Do not round intermediote colculotions, Enter your onswer os o percentage pounded to 2 decimst pinces. Omit the " "N" sign in your response.)