The building that I would imagine would be 40 stories, about 404 feet tall perhaps. If he were to throw the donut from that distance until the ground, catching it would be impossible. So no, I am not confident in catching the donut all the way there.
ac> bc is always true. This is beacuse c is multiplied to both a and b, and since a> b then ac will have a higher value than bc. Hence ac> bc is always true under the condition a> b.