The cafeteria bought 50 kilograms of rice and ate (1/5), how many kilograms are left.
食堂买来50千克大米，吃了(1/5)，还剩下多少千克．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">50 * (1/5)</gadget>
<output>10</output>

<gadget id="calculator">50 - 10</gadget>
<output>40</output>

<result>40</result>