The original price of a refrigerator is 4,500 yuan, and it is now on sale at a 20% discount. How much is the current price cheaper than the original price?
一台冰箱原价4500元，现八折出售，现价比原价便宜多少元？
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">4_500 * (1/5)</gadget>
<output>900</output>

<result>900</result>