Wang Ming reads a story book. He reads the whole book (1/5) in the morning and 45 pages in the afternoon. He reads half of the book in one day. How many pages does the book have?
王明看一本故事书，上午看了全书的(1/5)，下午看了45页，一天正好看了这本书的一半，这本书有多少页？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

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

<gadget id="calculator">(1/2) - (1/5)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">45 / (3/10)</gadget>
<output>150</output>

<result>150</result>