Wang Xiao reads a book, 8 pages a day, and can finish it in 15 days. To finish reading 7 days in advance, how many pages should be read each day? (Solve with ratio)
王晓读一本书，每天读8页，15天可以读完．要提前7天读完，每天应读几页？(用比例解)
<gadget id="calculator">8 * 15</gadget>
<output>120</output>

<gadget id="calculator">15 - 7</gadget>
<output>8</output>

<gadget id="calculator">120 / 8</gadget>
<output>15</output>

<result>15</result>