The school bought back 18 boxes of chalk, 6 boxes in each box, half of which were used up, how many boxes are left?
学校买回18箱粉笔，每箱6盒，用去了一半，还剩下多少盒？
<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">18 * 3</gadget>
<output>54</output>

<result>54</result>