1)5 4/9 - 3 5/9 = 49/9 - 32/9 = 17/9 = 1 8/9
2) 100 - 80 8/13 = 100/1 - 1048/13 =(100 × 13 - 1048 × 1)/13 = 1300/13 - 1048/13 = 252/13 = 19 5/13
3) 15 38/8 + 14 15/18 = 79/4 + 89/6 = (79 × 3 + 89 × 2)/12 = 237/12 + 178/12 = 415/12 = 34 7/12
4)24 3/8 - 12 1/8 = 195/8 - 97/8 = 195/8 - 97/8 = 98/8 = 49/4 = 12 1/4