Xiaoying reads a book and originally planned to finish it in 10 days. In fact, I read the whole book (2/5) two days ago. At this rate, how many days will it take to finish reading?
小英看一本书，原计划10天看完．实际前两天就看了全书的(2/5)．照这样的速度，还要多少天才能看完？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(2/5) / 2</gadget>
<output>1/5 = around 0.2</output>

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

<gadget id="calculator">5 - 2</gadget>
<output>3</output>

<result>3</result>