pile of grapefruits is divided into three boxes, each of the three boxes holds 30 pieces, and the rest is the original box, how many are in the original box.
一堆柚子分三个箱子装，三个箱子各拿30个，余下的是原来一个箱子，原来一个箱子多少个．
<gadget id="calculator">30 * 3</gadget>
<output>90</output>

<gadget id="calculator">90 / 2</gadget>
<output>45</output>

<result>45</result>