I have 42+8sqrt2+2sqrt10 over 18. Since it is 42 plus something I am unsure if I am able to reduce 42 to 7 and 18 to 3?? I know I can't simplify any more for the square roots but I was just wondering about the numbers.
To simplify a fraction you have to factor the numerator and the denominator. Equal factors can be cancelled because $\displaystyle \dfrac aa = 1~,~a \neq 0$:
$\displaystyle \dfrac{42+8\sqrt{2}+2\sqrt{10}}{18}=\dfrac{2\left( 21+4\sqrt{2}+\sqrt{10}\right)}{2 \cdot 9}$
... and now it's your turn.