1/4 + 9 3/7 = 1/4 + 66/7 = 1/4 + 28/28 = 29/28 + 28/28 = 57/28

7 1/12 + 6 = 7 + 6 + 1/12 = 13 + 1/12 = 13 1/12

5/7 + 3 1/4 = 5/7 + 13/4 = 20/28 + 91/28 = 111/28 = 3 27/28