Which statement is true when adding polynomials?

At a sand and gravel plant, sand is falling off a conveyor and onto a conical pile at a rate of 16 cubic feet per minute. the diameter of the base of the cone is approximately three times the altitude. at what rate is the height of the pile changing when the pile is 12 feet high? (hint: the formula for the volume of a cone is v = 1 3 πr2h.)

If the sales price of a dvd is $20 and the markup is 34%, what is the cost of the dvd?

Acd that is originally priced at $15.85 red-tagged for the sale. what is the sale price of the cd