There are 150 apple trees in the orchard, 50 more pear trees than apple trees, and 20 fewer orange trees than three times the number of pear trees. How many orange trees are there in the orchard?
果园里有苹果树150棵，梨树比苹果树多50棵，橘树棵数比梨树棵数的3倍少20棵．果园里有橘树多少棵？
<gadget id="calculator">150 + 50</gadget>
<output>200</output>

<gadget id="calculator">200 * 3</gadget>
<output>600</output>

<gadget id="calculator">600 - 20</gadget>
<output>580</output>

<result>580</result>