When Xiao Ming reads "The Romance of the Three Kingdoms", the ratio of the number of pages he has read to the number of unread pages is 5:4. If he reads another 27 pages, the ratio of the number of pages he has read to the number of unread pages is 2:1. how many pages
小明读《三国演义》，已读的和未读的页数之比为5：4，如果再读27页，已读的和未读的页数之比为2：1，求这本书有多少页？
<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">5 + 4</gadget>
<output>9</output>

<gadget id="calculator">5 / 9</gadget>
<output>5/9 = around 0.555556</output>

<gadget id="calculator">(2/3) - (5/9)</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">27 / (1/9)</gadget>
<output>243</output>

<result>243</result>