ASAP

He pays $15 per month and $0.20 per minute for local air time. Calvin signed up for another plan. He pays $25 per month and $0.10 per minute.

a) Write an equation representing Korey's cellular phone service.

b) Write an equation representing Calvin's cellular phone service.

c) Solve a system of equations to calculate when Cory's and Calvin's costs are the same. After how many minutes will this occur? write your answer in the form (x,y)
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