The price of a piece of clothing is 80 yuan, which is 20 yuan lower than the original price. By what percentage? How many.
一件衣服售价80元，比原价降低了20元．降低了百分之几？多少．
<gadget id="calculator">80 + 20</gadget>
<output>100</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

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