0,8*(1 2/3-0,6)-0,6*(5/9y-0,8)=8/10*5/3-8/10*6/10-6/10*5/9y+6/10*8/10=
=4/3-12/25-1/3y+12/25=4/3-1/3y=1 1/3-1/3y
0,9*(0,4-1 2/3m)-0,2*(0,8-7 1/2m)=9/10*4/10-9/10*5/3m-2/10*8/10+
+2/10*15/2m=9/25-3/2m-4/25+3/2m=1/5
-7/2х+1/3х-1/7х=-3 13/42х
-2/3у+5/21у+1/7у=-2/7