box of grapes weighs 28 kilograms, eat (1/4), how many kilograms are left.
一箱葡萄重28千克，吃了(1/4)，还剩多少千克．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">28 * (3/4)</gadget>
<output>21</output>

<result>21</result>