835.
1) ............=2/5*3/4*5/6*3/2*7/6*8/7=(2*3*5*3*7*8)/(5*4*6*2*6*7)=1/2
2) ........=1/3*1/4*1/2*6/5*3/2*12=9/10
3) ........=5/9*1/6*5/18*18*3/2*9=10/4=2 1/2
4) .......=3/5*2/15*1/12*6*5/2*10/3=10/30=1/3
836.
1) .......=(1/4+2/3-1/2) :(1/2-1/4+2/3)=(3/12+8/12-6/12):(6/12-3/12+8/12)=5/12 : 11/12=5/12 * 12/11=5/11
2) .......=(3/5-1/3-2/9):(7/15+2/3-4/5)=(27/45-15/45-10/45):(7/15+10/15-12/15)=2/45 : 1/3=2/45*3/1=2/15
3) ............=(4/15-1/6-1/12):(1/12+3/4-2/5)=(16/60-10/60-5/60):(5/60+45/60-24/60)=1/60:26/60=1/60*60/26=1/26
4) ........=(3/8+1/4+5/6):(1/2+2/3-1/8)=(9/24+6/24+20/24):(12/24+16/24-3/24)=35/24:25/24=12/24*24/2512/25