The students planted trees, and 190 willows were planted, 20 fewer than three times the number of fir trees. How many cedar trees were planted?
同学们植树，柳树植了190棵，比杉树的3倍少20棵．杉树植了多少棵？
<gadget id="calculator">20 + 190</gadget>
<output>210</output>

<gadget id="calculator">210 / 3</gadget>
<output>70</output>

<result>70</result>