Take (1/5) books from the upper shelf and put them in the lower shelf. The lower shelf is twice as many as the upper shelf. There are 140 original books in the lower shelf. How many original books are there in the upper shelf?
从书架上层取出(1/5)的书放入下层，下层是上层的2倍，下层原有书140本，上层原有书多少本？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

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

<gadget id="calculator">2 - (2/5) - (1/5)</gadget>
<output>7/5 = around 1.4</output>

<gadget id="calculator">140 / (7/5)</gadget>
<output>100</output>

<result>100</result>