A batch of 100 tons of goods was transported away in 4 hours (4/5). How many hours will the rest be shipped?
一批货物100吨，4小时运走了它的(4/5)．剩下的要几小时运完？
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">(4/5) / 4</gadget>
<output>1/5 = around 0.2</output>

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

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

<result>1</result>