X/3-1.2X/3=0.1x/3-12x/30=0.110x/30-12X/30=0.1-2X/30=0.1x=0.1*30/(-2)x=-3/2
解:(X-1.2X)/3=0.1 -0.2X=0.3 X=-3/2有帮助到你请采纳~