Question 610986
There are many ways to solve a problem. I believe this is the simplest way, and I think simpler is better. The three steps, as given in the problem, suggest the approach I'm using.
  
Step One:
100% - 24% = 76%
Cutting the number of pages by 24% leaves 76% of the original number of pages.
 
Step Two:
If the finished book contained 283 pages, then those 283 pages are 76% of the original number of pages.
How many pages were in the original form of the book?
It was a number that multiplied by {{{0.76}}} or {{{76/100}}} or 76% resulted in 283. (The expressions 0.76, {{{76/100}}} and 76% are different ways to express the same number, or ratio, or percentage). 
If you are in Algebra or Pre-algebra class, you would say that the book had {{{x}}} pages originally and it was cut down to
{{{0.76*x=283}}} pages, so {{{x=283/0.76}}}= about 372
If you are in 5th grade, you are so smart that you do not need any {{{x}}} to know that the answer is 283 divided by 0.76.
Actually, the result of the division was about 372.37, but we need a whole number of pages. Rounding gives us 372, so I would go with 372. That is the simpler answer, and I am betting that it is the expected answer.
However, 76% of 372 pages is 282.72, and 283 pages would be a little more than 76% of 372 pages. If your teacher (or textbook) likes more complicated calculations/answers, they may prefer 373 pages as the original length of the book.
 
Step Three:
If the finished book contained 283 pages, how many pages were cut?
If 372 pages were reduced to 283, the number of pages cut was
372 pages - 283 pages = 89 pages.
We could also calculate 24% of 372 as 372 times 0.24 = 89.28, but that's a harder, more complicated calculation. (And it hints that we should have cut more than 89 pages, making us doubt the simpler answer).
 
NOTE: If you like to argue for more complicated answers, just choose 373 pages as the original length and you would have cut 90 pages, which is about 24.1% of 373.