When Zhang Ling reads a story book, she has already read the whole book (2/5). After reading 16 pages, she can read half of the book. How many pages does this storybook have?
张玲看一本故事书，已经看了全书的(2/5)，再看16页，就能看完全书的一半．这本故事书共有多少页？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(1/2) - (2/5)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">16 / (1/10)</gadget>
<output>160</output>

<result>160</result>