Edwards read 68,820 chapters in the past 40 hours. The book has 108,839 Chapters. How much more dose he have to read to reach the whole book.

For the rule of 78, for a 12-month period, the last term in the sequence is 12 and the series sums to 78. for an 10 month period, the last term is and the series sum is . for a 15 month period, the last term is and the series sum is . for a 20 month period, the last term is and the series sum is