2\7(1,4х- 3целых1/2у)-1,2(5/6-0,5у)=
2/7·14/10x-2/7·7/2y-12/10·5/6+0,6y=0,4x-4-1+0,6y=0,4x-0,4y-1
24/35x-y-22/2*5/6-22/10*5/10= 24/35x-y-11/30 вроде так