On Sunday, Fangfang and Linlin helped Uncle Zhang water the fruit trees. Fangfang watered the 3 rows on the left and Linlin watered the 3 rows on the right. They watered 72 trees in total. How many trees are there on average in each row?
星期天，芳芳和琳琳帮张叔叔给果树浇水，芳芳浇左边3行，琳琳浇右边3行，两人一共浇了72棵，平均每行有几棵树？
<gadget id="calculator">3 + 3</gadget>
<output>6</output>

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

<result>12</result>