You can put this solution on YOUR website! Okay, first you need to factor (expand) each polynomial (group: the top of the fraction is a polynomial, and the bottom of the fraction is another polynomial).
X^2-13x+42 is the same as:
x^2-36 is the same as:
You can cross out both (x-6), from the top and the bottom. Here is what is left.
That is the simplified form. Hopefully that makes sense, and helps! :)