Answer:
The number of pages had Clint read prior to study hall were 127 pages.
Explanation:
Given:
Clint after 20 minutes is on page 151.
And, after 45 minutes he is on page 181.
Now, to find the pages Clint read prior to study hall.
The time difference = 45 minutes - 20 minutes.
= 25 minutes.
Difference between the pages = 181 - 151
= 30 pages.
If Clint is reading each page at same speed.
Then, in 25 minutes he can read = 30 pages.
So, in 1 minute he can read = 30 ÷ 25 = 1.2 pages.
Thus, in 20 minutes he can read

Now, number of pages Clint had read prior to study hall = 151 - 24
= 127 pages.
Therefore, the number of pages had Clint read prior to study hall were 127 pages.