Mom bought a box of apples and asked for 20 yuan. After bargaining, she paid 16 yuan. How much cheaper?
妈妈买一箱苹果，要价20元，经过还价，付了16元，便宜了几分之几？
<gadget id="calculator">20 - 16</gadget>
<output>4</output>

<gadget id="calculator">4 / 20</gadget>
<output>1/5 = around 0.2</output>

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