The school planted 45 poplars, 17 fewer willows than poplars, and 31 more metasequoias than willows. How many metasequoia trees are there?
校栽了45棵杨树，柳树比杨树少17棵，水杉树比柳树多31棵．水杉树有多少棵？
<gadget id="calculator">45 - 17</gadget>
<output>28</output>

<gadget id="calculator">28 + 31</gadget>
<output>59</output>

<result>59</result>