Which statement about the digital music pricing is true?

Can someone me with the property questions for 12 13 and 14 plz

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?

What is the equation, in point-slope form, of the line that has a slope of 6 and passes through the point (–1, –8)? a. y+8 = 6 (x+1 )