There are 310 pear trees in the orchard, and there are 100 fewer peach trees than twice the number of pear trees. How many peach and pear trees are there?
果园里有梨树310棵，桃树比梨树的2倍少100棵，桃树梨树共有多少棵？
<gadget id="calculator">310 * 2</gadget>
<output>620</output>

<gadget id="calculator">620 - 100</gadget>
<output>520</output>

<gadget id="calculator">520 + 310</gadget>
<output>830</output>

<result>830</result>