Xiaohong watered 3 rows of trees on the left, and Xiaojun watered 3 rows of trees on the right. They watered a total of 120 trees. How many trees are there in each row?
小红浇左边3行树，小军浇右边3行树，他们共浇了120棵树，每行有多少棵？
<gadget id="calculator">3 + 3</gadget>
<output>6</output>

<gadget id="calculator">120 / 6</gadget>
<output>20</output>

<result>20</result>