The cafeteria brings 5 tons of rice, eat it (2/5), how many tons are left
食堂运来5吨大米，吃去(2/5)，还剩多少吨
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">5 * (3/5)</gadget>
<output>3</output>

<result>3</result>