x=0.6
解：
1.25×3.2-6x=0.4
1.25×0.8×4-6x=0.4
1×4-6x=0.4
6x=4-0.4
6x=3.6
x=3.6/6
1.25*3.2-6x=0.4 4-6x=0.4 -6x=-3.6 x=0.6
