解答:解:設(shè)規(guī)定x天讀完,
35×(x+1)=40x﹣5,
35x+35=40x﹣5,
5x=40,
x=8;
書的總頁數(shù)為:40x﹣5=40×8﹣5=315(頁);
最后一天應(yīng)讀:315﹣(8﹣1)×39
=315﹣273
=42(頁);
答:最后一天應(yīng)讀42頁才按規(guī)定時間讀完.