On Wednesday, Billy read ⁵₇ of a textbook. On Thursday, he read 34 pages of the textbook. On Friday, he read ³₈ of the remaining book leaving 40 pages unread.

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

(a)
Number of remaining unread pages after reading on Thursday = 8 u

Number of remaining unread pages after reading on Friday
= 8 u - 3 u
= 5 u

5 u = 40

1 u = 40 ÷ 5 = 8

Number of pages that Billy read on Friday
= 3 u
= 3 x 8
= 24

(b) 
Working backwards.

Number of pages unread after reading on Thursday
= 8 u
= 8 x 8
= 64

Total number of pages in the textbook = 7 p

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

2 p = 34 + 64
2 p = 98

1 p = 98 ÷ 2 = 49

Total number of pages in the textbook
= 7 p
= 7 x 49
= 343

Answer(s): (a) 24; (b) 343