On Wednesday, Tommy read ³₇ of a guide book. On Thursday, he read 38 pages of the guide book. On Friday, he read ⁵₇ of the remaining book leaving 20 pages unread.

1. Find the number of pages read on Friday.
2. Find the total number of pages in the guide book.

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

Number of remaining unread pages after reading on Friday
= 7 u - 5 u
= 2 u

2 u = 20

1 u = 20 ÷ 2 = 10

Number of pages that Tommy read on Friday
= 5 u
= 5 x 10
= 50

(b) 
Working backwards.

Number of pages unread after reading on Thursday
= 7 u
= 7 x 10
= 70

Total number of pages in the guide book = 7 p

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

4 p = 38 + 70
4 p = 108

1 p = 108 ÷ 4 = 27

Total number of pages in the guide book
= 7 p
= 7 x 27
= 189

Answer(s): (a) 50; (b) 189