Assuming the cans reach from the bottom to the top of the box and they are in a single row then the volume of the box is (12 x15) x 15 x 24 = 64800 cubic cm. The volume of each tin is pi x r squared x h = 4241.15 (2 decimal places) which given there are 12 cans makes a total volume of 50893.80 cubic centimetres. This means that the volume of empty space is 13906.19901 cubic cm. This does assume the cans are packed in a single row in the box and reach the edge of the box in all 3 dimensions, if this is not the case we need to know how they are stacked to give the solution.