Kathi is trying to buy herself a phone. She is deciding between Phone Plan A and B.
phone plan A = retail price : $500 cupon : 25% off sale price : x

phone plan B = retail price : $435 cupon : 50% off sale price : x

How can she find out the monetary amount of the discount for Phone Plan A?

a. x/500 = 24/100

b. 25/500 = x/100

c. x/25 = 100/500

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