(1)x-0.9x=5.8,
0.1x=5.8,
0.1x÷0.1=5.8÷0.1,
x=58;
(2)2x-0.6×0.4=0.4,
2x-0.24=0.4,
2x-0.24+0.24=0.4+0.24,
2x=0.64,
2x÷2=0.64÷2,
x=0.31;
(1)x-0.9x=5.8,
0.1x=5.8,
0.1x÷0.1=5.8÷0.1,
x=58;
(2)2x-0.6×0.4=0.4,
2x-0.24=0.4,
2x-0.24+0.24=0.4+0.24,
2x=0.64,
2x÷2=0.64÷2,
x=0.31;