After a price reduction of 10 yuan, the price of a commodity is 40 yuan, how much is it reduced?
一种商品降价10元后售价为40元，降低了多少．
<gadget id="calculator">10 + 40</gadget>
<output>50</output>

<gadget id="calculator">10 / 50</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>