小学法:(6.3×1/7-0.15)÷3=(0.9-0.15)÷3=0.75÷3=0.25中学法:设这个数为x3x=6.3×1/7-0.153x=0.9-0.153x=0.75x=0.25
解:设这个数是X6.3×1/7-3X=0.150.9-3X=0.153X=0.9-0.15X=0.75÷3X=0.25
设该数为X,则3x=6.3*1/7-0.15x=0.25