6.4(у-12.8)=3.2 6.4у-81.92=3.2 6.4у=3.2+81.92 6.4у=85.12 у=85.12:6.4 у=13.3 3.4х+8.1х-2.3=20.7 11.5х=20.7+2.3 11.5х=23 х=23:11.5 х=2