Aunt Wang went to a certain market to buy vegetables. She bought 500g of cucumbers for 1 yuan and 80 cents, and bought 2kg of beans for 20 yuan. How much is it cheaper per kilogram of cucumber than per kilogram of beans?
王阿姨到某市场买菜，买500g黄瓜花了1元8角，买2kg豆角花了20元，每千克黄瓜比每千克豆角便宜多少钱？
<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">8 / 10</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 + (4/5)</gadget>
<output>9/5 = around 1.8</output>

<gadget id="calculator">500 / 1_000</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(9/5) / (1/2)</gadget>
<output>18/5 = around 3.6</output>

<gadget id="calculator">10 - (18/5)</gadget>
<output>32/5 = around 6.4</output>

<result>32/5 = around 6.4</result>