There are many kinds of trees in a forest, 1500 trees are not pine trees, 1200 trees are not poplar trees, a total of 700 pine trees and poplar trees. How many poplar trees?
一片树林里有很多种树，有1500棵树不是松树，1200棵树不是杨树，松树和杨树共700棵．杨树多少棵？
<gadget id="calculator">1_500 - 1_200</gadget>
<output>300</output>

<gadget id="calculator">700 + 300</gadget>
<output>1_000</output>

<gadget id="calculator">1_000 / 2</gadget>
<output>500</output>

<result>500</result>