Divide 4 and 9 by 2 that will give you the size of a 2 in ribbon curl then add that back to the original 4 in Ribbon curl to make a 6 in
4 and 9 / 2 = 2 and 4.5 then add this to the 4in ribbon curl and out of 9in to make a 6in ribbon curl you need 13.5inches of ribbon