(1)0.8-0.49x=0.310.49x=0.8-0.310.49x=0.49x=0.49÷0.49x=1(2)8.5(x-1.2)=68x-1.2=68÷8.5x-1.2=8x=8+1.2x=9.2(3)3.4÷x=4.8÷243.4-x=0.2x=3.4-0.2x=3.2(4)8-3(x+0.2)=0.83(x+0.2)=8-0.83(x+0.2)=7.2x+0.2=7.2÷3x+0.2=2.4x=2.4-0.2x=2.2未完待续~