1.6+0.7x=19.8 1.6x-0.8=2.4
2.7(x-2)=10.8 4.2x-x=1.28
①x-7.8= 13.02
②0.8(x-1.5)=6.48
③12.4-4x=2.4
④4.7x+2.1x=68.68