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Solve the system of equations. y= 2x y= x^2 - 15

Molly shared a spool of ribbon with 12 people. each person received 3 feet of ribbon. which equation can she use to find r, the number of feet of ribbon that her spool originally had?

The cost of using a service is $0.25 per min. what equation correctly represents the total cost c, in dollars, for d days of use?