There is a bucket of pure water, 40% is taken out for the first time, and 10 kg less than the first time is taken out for the second time, leaving 30 kg of pure water in the bucket. How many kilograms does this bucket of pure water weigh?
有一桶纯净水，第一次取出40%，第二次比第一次少取出10千克，桶里还剩30千克纯净水．这桶纯净水原来有多少千克？
<gadget id="calculator">30 - 10</gadget>
<output>20</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5) - (2/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">20 / (1/5)</gadget>
<output>100</output>

<result>100</result>