There are 310 apple trees in the orchard, 120 more peach trees than apple trees, and 200 fewer pear trees than peach trees. How many pear trees are there in the orchard?
果园里有苹果树310棵，桃树比苹果树多120棵，梨树比桃树少200棵，果园里有梨树多少棵？
<gadget id="calculator">120 - 200</gadget>
<output>-80</output>

<gadget id="calculator">310 + (-80)</gadget>
<output>230</output>

<result>230</result>