You can write it out as:
N+(N+1)+(N+2) = 132
Then you can simplify:
3N+3 = 132
Then you can minus 3 from both sides:
3N+3-3 = 132-3
3N = 129
...And divide both sides by 3
3N / 3 = 129 / 3
N = 43
If you look at the equation above( N+(N+1)+(N+2)=132 ) you see that the third number is equal to (N+2), thus:
N+2 = 43+2 = 45
So the third number is equal to 45.
Hope this helps! :)