Kaitlyn had 12a+21 marbles. she gave one third of the marbles to her friend john. how many marbles does she have left

The jones farm has 24 cows that each produce 52 quarts of milk a day. how many quarts are produced each day altogether

Abox contains 1 plain pencil and 4 pens. a second box contains 5 color pencils and 5 crayons. one item from each box is chosen at random. what is the probability that a plain pencil from the first box and a color pencil from the second box are selected? write your answer as a fraction in simplest form.

Astuntman jumping off a 20-m-high building is modeled by the equation h=20-5t^2, where t is the same in seconds. a high-speed camera is ready to film him between 15m and 10m above the ground. for which interval of time should the camera film him?