For a barrel of gasoline, the full barrel (1/5) was used on the first day, and the rest (1/2) was used on the second day, leaving 600 liters. How many liters is this barrel of oil?
一桶汽油，第一天用了全桶的(1/5)，第二天用了剩下的(1/2)，还剩600升，这桶油有多少升？
<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">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/2)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(4/5) * (1/2)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">600 / (2/5)</gadget>
<output>1_500</output>

<result>1_500</result>