Answer :
if you have 12 pr's, and you take 3 away... you're left with 9 pr's....
12pr + 2st - 3pr -8rs
9pr +2st - 8rs
Now, there are no two of the same thing.. so you can't factorize anymore.
12pr + 2st - 3pr -8rs
9pr +2st - 8rs
Now, there are no two of the same thing.. so you can't factorize anymore.