A bottle of potion, 75% of it is used up and 3 liters are used, how many liters is the bottle of potion originally?
一瓶药水，用去它的75%用去了3升，这瓶药水原来有多少升．
<gadget id="calculator">75 / 100</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">3 / (3/4)</gadget>
<output>4</output>

<result>4</result>