Answer
The three pages are numbered $32,33,34.$
Work Step by Step
$\bf{\text{l. Familiarize yourself with the problem.}}$
If the first page number is $x$,
then the next two are $x+1$ and $x+2$.
We need the sum of $x,\ x+1$, and $x+2$ to be 99.
$\bf{\text{2. Translate to mathematical language.
(This often means writing an equation.)}}$
$x+x+1+x+2=99$
$\bf{\text{3. Carry out some mathematical manipulation.
(This often means solving an equation.)}}$
$3x+3=99$
$3x=96$
$x=32$,
The next two are 33 and 34.
The three pages are numbered $32,33,34.$
$\bf{\text{4. Check your possible answer in the original problem.}}$
Is $32+33+34=99$?
Yes.
$\bf{\text{5. State the answer clearly, using a complete sentence.}}$
The three pages are numbered $32,33,34.$
