Huanhuan reads a world famous book, and reads an average of 12 pages a day. After reading for 15 days, she finds that there are still 9 pages left unread. How many pages does this world famous book have?
欢欢读一本世界名著，平均每天读12页，读了15天，发现还有9页没有读，这本世界名著共有多少页？
<gadget id="calculator">12 * 15</gadget>
<output>180</output>

<gadget id="calculator">180 + 9</gadget>
<output>189</output>

<result>189</result>