On Monday, Carl read ⁵₇ of a story book. On Tuesday, he read 31 pages of the story book. On Wednesday, he read ⁴₇ of the remaining book leaving 15 pages unread.

1. Find the number of pages read on Wednesday.
2. Find the total number of pages in the story book.

(a)
Number of remaining unread pages after reading on Tuesday = 7 u

Number of remaining unread pages after reading on Wednesday
= 7 u - 4 u
= 3 u

3 u = 15

1 u = 15 ÷ 3 = 5

Number of pages that Carl read on Wednesday
= 4 u
= 4 x 5
= 20

(b) 
Working backwards.

Number of pages unread after reading on Tuesday
= 7 u
= 7 x 5
= 35

Total number of pages in the story book = 7 p

Number of pages unread after reading on Monday 
= 7 p - 5 p
= 2 p

2 p = 31 + 35
2 p = 66

1 p = 66 ÷ 2 = 33

Total number of pages in the story book
= 7 p
= 7 x 33
= 231

Answer(s): (a) 20; (b) 231