The green area of a primary school this year has increased by 20% compared to last year. What is the green area of last year?
某小学今年绿化校园的面积比去年增加20%，去年绿化面积是今年的多少
<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">1 / (6/5)</gadget>
<output>5/6 = around 0.833333</output>

<result>5/6 = around 0.833333</result>