A bottle of oil is eaten for the first time (1/5), and the rest (3/4) is eaten for the second time. At this time, there is still (1/5) kilograms in the bottle. How many kilograms is the bottle of oil originally?
一瓶油第一次吃去(1/5)，第二次吃去余下的(3/4)，这时瓶内还有(1/5)千克，这瓶油原来有多少千克？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">(1/5) / (1/4) / (4/5)</gadget>
<output>1</output>

<result>1</result>