If 20% of 500 kg of flour is eaten, and the remaining 20% is eaten, how many kilograms are eaten in total?
500千克面粉吃去20%，又吃了余下的20%，共吃去多少千克．
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">500 * (1/5)</gadget>
<output>100</output>

<gadget id="calculator">500 - 100</gadget>
<output>400</output>

<gadget id="calculator">400 * (1/5)</gadget>
<output>80</output>

<gadget id="calculator">100 + 80</gadget>
<output>180</output>

<result>180</result>