A book has 640 pages, and I read it (3/8) in 3 days. How many days will it take to finish this book at this speed?
一本书640页，3天看了它的(3/8)，照这样的速度还要几天才能看完这本书？
<gadget id="calculator">3 / 8</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">1 - (3/8)</gadget>
<output>5/8 = around 0.625</output>

<gadget id="calculator">(3/8) / 3</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">(5/8) / (1/8)</gadget>
<output>5</output>

<result>5</result>