A barrel of oil is 10 kilograms in total. The first time (1/5) is used, and the second time (2/5), how many kilograms of oil are used in total? (answer in two ways)
一桶油总共10千克，第一次用去(1/5)，第二次用去(2/5)，一共有去多少千克油？(用两种方法解答)
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">10 * (1/5)</gadget>
<output>2</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(2/5) * 10</gadget>
<output>4</output>

<gadget id="calculator">2 + 4</gadget>
<output>6</output>

<result>6</result>