What is 1/2 minus 1/4?

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.)

Pls will give brainliest and all p.s u can zoom in if u cant see plss

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