25% of a bucket of purified water has been used, leaving 3kg. How many kilograms does this bucket of pure water weigh?
一桶纯净水用了25%，还剩3kg．这桶纯净水原来有多少千克？
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">3 / (3/4)</gadget>
<output>4</output>

<result>4</result>