In the "Green Lake Building" activity, the sixth grade of Yuhong Primary School planted 414 trees this year, an increase of 15% over last year. How many trees were planted last year?
在"绿色建湖"活动中，育红小学六年级今年植树414棵，比去年增加了15%，去年植树多少棵？
<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">1 + (3/20)</gadget>
<output>23/20 = around 1.15</output>

<gadget id="calculator">414 / (23/20)</gadget>
<output>360</output>

<result>360</result>