Xiao Ming reads an extra-curricular book. He reads 25 pages a day for the first 6 days, and then reads 15 more pages a day. After another 4 days, he finishes reading it. How many pages does this extra-curricular book have?
小明读一本课外书，前6天每天读25页，以后每天多读15页，又经过4天正好读完，这本课外书有多少页？
<gadget id="calculator">25 * 6</gadget>
<output>150</output>

<gadget id="calculator">25 + 15</gadget>
<output>40</output>

<gadget id="calculator">40 * 4</gadget>
<output>160</output>

<gadget id="calculator">150 + 160</gadget>
<output>310</output>

<result>310</result>