a: =>x+1/3=1/2-5/6=3/6-5/6=-1/3
=>x=-2/3
b: =>2/3x=3/10-5/7=21/70-50/70=-29/70
=>x=-29/70:2/3=-29/70*3/2=-87/140
c: =>1/4:x=2/5-3/4=8/20-15/20=-7/20
=>x=-1/4:7/20=-1/4*20/7=-20/28=-5/7
d: =>11/10x=-33/25
=>x=-33/25:11/10=-33/25*10/11=-330/25*11=-30/25=-6/5