The water in a water tank is full (5/6). After 20 liters of water are used, the remaining water is full (3/4). What is the volume of the water tank in liters?
一个水箱中的水是装满时的(5/6)，用去20升水后，剩余的水是装满时的(3/4)，求这个水箱的容积是多少升？
<gadget id="calculator">5 / 6</gadget>
<output>5/6 = around 0.833333</output>

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

<gadget id="calculator">(5/6) - (3/4)</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">20 / (1/12)</gadget>
<output>240</output>

<result>240</result>