(100X75%)/40%-100=87.5ml另一解法：75%酒精重量百分比是67.8246%密度是0.87277,100ml中就有纯酒精59.195g40%酒精重量百分比是33.3004%密度是0.94806,59.195/(33.3004%X0.94806)=187.49即187.49ml40%酒精中也有纯酒精59.195g,答案也是87.5ml
