A batch of coal used up all (3/4). Another 240 tons were transported. At this time, there is only the original (1/2), how many tons of coal are there?
一批煤用去了全部的(3/4)．又运进240吨．这时也只有原来的(1/2)，原来有煤多少吨？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

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

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/2) - (1/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">240 / (1/4)</gadget>
<output>960</output>

<result>960</result>