8х-(7х-142)=51 (6-2х)+4=5х+5,5 9-(8х-11)=12
8х-7х+142=51 (6-2х)+4=5х+5,5 9-(8х-11)=12
х+142=51 6-2х+4=5х-5,5 9-8х+11=12
х=142-51 -2х+5,5х=-6-4 9+11-12=8х
х=91 3,5х=-10 8=8х
х=-0,35 х=1