Congcong reads a book, and he reads 15 more pages of this book on the first day (2/9). According to this speed, he can finish reading in 4 days. How many pages does Congcong read on average every day?
聪聪读一本书，他第一天读了这本书的(2/9)还多15页，照这样的速度，4天可以读完．聪聪平均每天读多少页？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">(1/4) - (2/9)</gadget>
<output>1/36 = around 0.027778</output>

<gadget id="calculator">15 / (1/36) / 4</gadget>
<output>135</output>

<result>135</result>