When Xiaohong prints a manuscript, the ratio of the number of pages printed on the first day to the total number of pages in the manuscript is 1:3. If she prints 15 pages on the second day, half of the entire manuscript can be printed. How many pages does this manuscript have?
小红打印一份稿件，第一天打印的页数与稿件总页数的比是1：3，如果第二天打印15页，就可以打印完全部稿件的一半．这份稿件一共有多少页？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/2) - (1/3)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">15 / (1/6)</gadget>
<output>90</output>

<result>90</result>