24 ft is 24/3 = 8 yards
30 ft is 30/3 = 10 yards
5 inches is 5/36 yards.
Thus the volume is
8 10 5/36 = 11.1 cubic yards.
You can calculate this and similar volumes using our volume calculator.
Use this calculator to find the amount of concrete, cement, topsoil or water you need for a rectangular solid shape when you know the length, width and depth.
Most often, when you order concrete or large amounts of topsoil, orders and deliveries are done in cubic yards (which are often just called "yards").