9 and 1/12 inches of pipe remain because 30 and 3/4 = 30 and 9/12 4 and 1/3 = 4 and 4/12 4 and 4/12 x 5 = 20 and 20/12 which can be simplified to 21 and 8/12 30 and 9/12 - 21 and 8/12 = 9 and 1/12.
9 and 1/12 inches. So 5 times 4 1/3 would be 65/3 which is the same as 260/12. 30 3/4 would be 369/12-260/12 which is 109/12, it then becomes 9 and 1/12 inches
