Grandpa's orchard was planted with peach and pear trees. He counted them and found that there were 36 trees in total. He also found that the number of peach trees was twice that of pear trees. How many pear trees are there in grandpa's orchard?
爷爷的果园种着桃树和梨树，明明数了数，发觉一共有36棵，他还发现桃树的棵数是梨树的2倍．爷爷的果园里种着梨树多少棵？
<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<gadget id="calculator">36 / 3</gadget>
<output>12</output>

<result>12</result>