There are 552 peach trees, pear trees, and apple trees in the orchard. Peach trees are 12 times more than pear trees, and apple trees are 20 fewer than pear trees. How many pear trees are there?
果园里有桃树、梨树、苹果树共552棵．桃树比梨树的2倍多12棵，苹果树比梨树少20棵．梨树有多少棵．
<gadget id="calculator">552 - 12</gadget>
<output>540</output>

<gadget id="calculator">20 + 540</gadget>
<output>560</output>

<gadget id="calculator">2 + 1 + 1</gadget>
<output>4</output>

<gadget id="calculator">560 / 4</gadget>
<output>140</output>

<result>140</result>