19
Пошаговое объяснение:
1)3.15/28:9/28=99*28/9/28=99*28/28*9=11
2)1:1.10/49=1:59/49=49/59
3)11-49/59=10.10/59=600/59
4)2/5*600/59=240/59
5)240/59:2/1=240/59*2=120/59
6)21.2/59-120/59=1241/59-120/59=1121/59=19
