1} 5 4/9 - 3 5/9 =? 2} 100-80 8/13=? 3} 15 3/8+14 15/18=? 4}24 3/8 -12 1/8=? 99

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