On June 1st, children's books in bookstores are sold at a 20% discount. The current price of a set of children's books is 160 yuan, so how much cheaper is it.
"六一"节，书店的儿童读物打八折出售，一套儿童读物的现价160元，那么便宜了多少元．
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">160 / (4/5)</gadget>
<output>200</output>

<gadget id="calculator">200 - 160</gadget>
<output>40</output>

<result>40</result>