Two bags of rice, the first bag weighs 45 kg, the second bag is 1/5 lighter than the first bag, how much does the second bag weigh in kilograms?
两袋大米，第一袋重45千克，第二袋比第一袋轻(1/5)，第二袋大米重多少千克．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">45 * (4/5)</gadget>
<output>36</output>

<result>36</result>