barrel of oil weighs 40 kilograms. The first time (1/3) is used, and the rest (3/5) is used for the second time. What fraction of the barrel of oil is used for the second time?
一桶油重40千克，第一次用去了(1/3)，第二次用去剩下的(3/5)，第二次用去这桶油的几分之几？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 - (1/3)</gadget>
<output>2/3 = around 0.666667</output>

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

<gadget id="calculator">(2/3) * (3/5)</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>