X(x+3)-7(x+3)
x2+3x-7x-21
x^2-4x-21
I'm assuming all of (x^2+9) is in the denominator. If that assumption is correct, then,
One possible answer is 
Another possible answer is 
There are many ways to do this. The idea is that when we have f( g(x) ), we basically replace every x in f(x) with g(x)
So in the first example above, we would have

In that third step, g(x) was replaced with x^2+9 since g(x) = x^2+9.
Similar steps will happen with the second example as well (when g(x) = x^2)
X is 19
Explanation: because the opposite side of the angle is 134 degrees the other side also has to be 134 degrees. So we do 134-20 which is 114 and then 114 divided by 6 because the number next to x is 6 and the number that is x has to be 19 as 19x6 is 114.
I think this is the right answer and I hope it helps :)