To dilute 150 kg of 95% alcohol into 75% alcohol, how many kg of water should be added?
把浓度为95%的酒精150千克稀释为75%的酒精，需加水多少千克．
<gadget id="calculator">95 / 100</gadget>
<output>19/20 = around 0.95</output>

<gadget id="calculator">75 / 100</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">(19/20) / (3/4)</gadget>
<output>19/15 = around 1.266667</output>

<gadget id="calculator">150 * (19/15)</gadget>
<output>190</output>

<gadget id="calculator">190 - 150</gadget>
<output>40</output>

<result>40</result>