Xiaodong bought a copy of "Fairy Tales", and planned to read 15 pages a day and finish it in a week. If you want to read it 2 days in advance, how many pages do you need to read on average every day?
小东买了一本《童话故事》，计划每天看15页，一周看完．如果要提前2天看完，平均每天至少需要看多少页？
<gadget id="calculator">7 - 2</gadget>
<output>5</output>

<gadget id="calculator">7 / 5</gadget>
<output>7/5 = around 1.4</output>

<gadget id="calculator">15 * (7/5)</gadget>
<output>21</output>

<result>21</result>