1) 1- 7/8+2/27=189/216+16/216=205/216
2- 205/216:5/9=205*9/216*5=41/24
3- 1/6+41/24=4/24+41/24=45/24=15/8
4- 3/11*2 1/5=3*11/11*5=3/5
5- 15/8+3/5=75/40+24/40=99/40=2 19/40
2) 1- 2:1/4=2*4/1*1=8
2- 1 1/2+2 2/3=3/2+8/3=9/6+16/6=25/6
3- 25/6:3 3/4=25*4/6*15=10/9
4- 10/9-2/3=10/9-6/9=4/9
5- 4/9:8 8/9=4*9/9*80=1/20
3) 1- 11/18-1/15=55/90-6/90=49/90
2- 49/90:1 2/5=49*5/90*7=7/18
3- 7/18-1/5=35/90-18/90=17/90
4- 17/90*8/25:1/50=17*8*50/90*25*1=17*8/5*9=136/45
5- 8/15+136/45=24/45+136/45=160/45=32/9=3 5/9