Answer:
difference of cost between two company = 12 - 0.12 x
Explanation:
For company ABC
start up fee = $12
cost of one minute call = $0.08
if x minute call are done then cost of x call = 0.08*x = 0.08x
total cost incurred in company ABC= startup fee+ cost of x minute call = 12+0.08X
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For company WYZ
start up fee = 0
cost of one minute call = $0.20
if x minute call are done then cost of x call = 0.20*x = 0.20x
total cost incurred in company WYZ plan = startup fee+ cost of x minute call = 0+0.20x = 0.20x
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difference of cost between two company = 12+0.08x - 0.20x
difference of cost between two company = 12 - 0.12x (Answer)