On Tuesday, Tim read ³₅ of a textbook. On Wednesday, he read 33 pages of the textbook. On Thursday, he read ²₅ of the remaining book leaving 21 pages unread.

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

(a)
Number of remaining unread pages after reading on Wednesday = 5 u

Number of remaining unread pages after reading on Thursday
= 5 u - 2 u
= 3 u

3 u = 21

1 u = 21 ÷ 3 = 7

Number of pages that Tim read on Thursday
= 2 u
= 2 x 7
= 14

(b) 
Working backwards.

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

Total number of pages in the textbook = 5 p

Number of pages unread after reading on Tuesday 
= 5 p - 3 p
= 2 p

2 p = 33 + 35
2 p = 68

1 p = 68 ÷ 2 = 34

Total number of pages in the textbook
= 5 p
= 5 x 34
= 170

Answer(s): (a) 14; (b) 170