Xiaoming planted 3 rows of trees, and Xiaoli also planted 3 rows, with 12 trees in each row. How many trees did they plant in total?
小明种了3行树，小丽也种了3行，每行种12棵，他们一共种了多少棵树？
<gadget id="calculator">3 + 3</gadget>
<output>6</output>

<gadget id="calculator">6 * 12</gadget>
<output>72</output>

<result>72</result>