A book has 800 pages, and 3/8 of the total number of pages were read in the first three days. According to this calculation, how many days will it take to finish reading? (Solve with ratio)
一本书800页，前三天看总数的(3/8)，照这样计算余下还要几天看完？(用比例解)
<gadget id="calculator">800 * 3</gadget>
<output>2_400</output>

<gadget id="calculator">3 / 8</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">800 * (3/8) * 3</gadget>
<output>900</output>

<gadget id="calculator">2_400 - 900</gadget>
<output>1_500</output>

<gadget id="calculator">800 * (3/8)</gadget>
<output>300</output>

<gadget id="calculator">1_500 / 300</gadget>
<output>5</output>

<result>5</result>