1) 3 15/28:2/28=99/28:2/28=99/28*28/2=99/2
2) 1: 1 40/49=49/49: 89/49=49/49*49/89=49/89
3) 99/2- 49/89=8811-98/89=8713/89
4) 2/5*8713/89=17426/445
5) 17726/445: 2= 17726/445*1/2=8863/445
6) 21 2/59- 8868/445= 1241/59- 8868/445=552245-523212/26255=29033/26255=1целая 2778/26255