-4х-8(9-2х)=-4х-72+16х= 12х-72
1/3(12-2,1у)+0,3у=4-1/3*21/10у+0,3у= 4-7/10у+3/10у= 4-у
6(3х-2)+4(5х-1)= 18х-12+20х-4= 38х-16
-7(3-4с)+14(0,5+2с)=-21+28с+7+28с= 56с-14
3(2,1х-у)-2,8(2х-3у)= 6,3х-3у-5,6х+8,4у= 0,7х+5,4у
0,4(8т+7)-1,6(2т-3)=3,2т+2,8-3,2т+4,8= 7,6