(1)42-6Χ=15.6, 42-6Χ+6x=15.6+6x, 42-15.6=15.6+6x-15.6, 26.4=6x, 26.4÷6=6x÷6, x=4.4;(2)Χ:0.2= 2 3 :0.8, 0.8x=0.2× 2 3 , 0.8x÷0.8= 2 15 ÷0.8, x= 1 6 .