First you need to change the mix fraction which is 9 1/6 - 3 7/8 to 55/6 - 31/8. Then you need to find the least common denominator which is 24 so you'd take 55/6 and multiply both the top and bottom by 4 then for 31/8 you multiply the top and bottom by 3 which would give you 220/24 - 93/24 which equals 127/24 which would reduce to 5 7/24