There is a barrel of oil, 30% of which is used for the first time, and (3/5) is used for the second time, leaving 2.3 kilograms. How many kilograms is this barrel of oil?
有一桶油，第一次用去30%，第二次又用去(3/5)，还剩下2.3千克，这桶油原来是多少千克？
<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 - (3/10) - (3/5)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">2.3 / (1/10)</gadget>
<output>23</output>

<result>23</result>