The cafeteria brings (1/5) ton of flour, eats (1/6) ton, how many tons are left.
食堂运来(1/5)吨面粉，吃了(1/6)吨，还剩多少吨．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(1/5) - (1/6)</gadget>
<output>1/30 = around 0.033333</output>

<result>1/30 = around 0.033333</result>