30% of a barrel of oil is poured out, which is exactly 9 kilograms. How many kilograms does this barrel of oil weigh?
一桶油倒出30%，正好倒出9千克．这桶油重多少千克？
<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">9 / (3/10)</gadget>
<output>30</output>

<result>30</result>