## 178. Math Puzzle $3 / 80$

Sven had borrowed a book from the children's library. At first, he read exactly twelve pages every day; after eight days, he had read half of the book. To meet the loan period, he had to read four more pages each day from the ninth day onwards.

a) How many pages did the book have?

b) For how many days did Sven borrow the book?
a) After eight days, Sven had read half of the book. That was $8 \cdot 12=96$ pages.

b) The second half of the book, which was 96 pages, Sven read in stages of $12+4=16$ pages each. He needed $96: 16=6$ days for this.

The total loan period was therefore $8+6=14$ days.