240 trees were planted this year, 20% more than last year. How many trees were planted last year?
今年栽树240棵，比去年多栽20%，去年栽了多少棵？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 + (1/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">240 / (6/5)</gadget>
<output>200</output>

<result>200</result>