There are 309 pine trees in a plantation, and the number of willow trees is 50 more than three times that of pine trees. How many willow trees are there?
一片人工林里有309棵松树，柳树的棵数比松树的3倍多50棵，柳树有多少棵？
<gadget id="calculator">309 * 3</gadget>
<output>927</output>

<gadget id="calculator">927 + 50</gadget>
<output>977</output>

<result>977</result>