The school bought 3 boxes of basketballs, 6 in each box, and 9 balls. How many basketballs did the school buy?
学校买了3箱篮球，每箱6个，还买了9个皮球，学校买了多少个篮球．
<gadget id="calculator">3 * 6</gadget>
<output>18</output>

<result>18</result>