Xiaoliang reads a 354-page science and technology book. He reads an average of 15 pages a day in the first 8 days, and plans to read 18 pages a day for the rest. How many days will it take Xiaoliang to finish reading this book?
小亮看一本354页的科技书，前8天平均每天看15页，剩下的计划每天看18页．小亮看完这本书一共需要多少天？
<gadget id="calculator">15 * 8</gadget>
<output>120</output>

<gadget id="calculator">354 - 120</gadget>
<output>234</output>

<gadget id="calculator">234 / 18</gadget>
<output>13</output>

<gadget id="calculator">13 + 8</gadget>
<output>21</output>

<result>21</result>