What is the slope of (20,15) (20,50)

Compare the cost of the bike trips from the two companies shown.for both the cost in a linear function of the number of days which statements is true

Florence price's brownies and more sells all types of cookies and pastries. on tuesdays, they markdown all brownies 75% to a sale of $1.50 a dozen. find the selling price and the markdown of a dozen brownies.

Having a hard time understanding this question (see attachment).