A batch of steel weighs (5/9) tons, if (1/4) ton is used up, how many tons are left?
一批钢材重(5/9)吨，用去(1/4)吨，还剩多少吨？
<gadget id="calculator">5 / 9</gadget>
<output>5/9 = around 0.555556</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(5/9) - (1/4)</gadget>
<output>11/36 = around 0.305556</output>

<result>11/36 = around 0.305556</result>