Answer:
45
Step-by-step explanation:
The lowest same number that you can get from multiplying the denominator!
Hope this help!
Answer: 
Work Shown:
I'm assuming your teacher wants you to factor as much as possible.

In the last step, I used the rule that 
We cannot factor any further. If the first term was
instead of
, then we could use the difference of squares factoring rule.
F(x)=(x-8)/(x+7). g(x)=(-7x-8)/(x-1). Plug in g(x) into f(x), f(g(x))=[(-7x-8)/(x-1)-8]/[-7x-8)/(x-1)+7], which can be simplified as (-7x-8-8x+8)/(-7x-8+7x-7)=-15x/-15=x. Plug in f(x) into g(x), g(f(x))=[-7*(x-8)/(x+7)-8]/[(x-8)/(x+7)-1]=(-7x+56-8x-56)/(x-8-x-7)=-15x/-15=x, as desired.