Let f(x) = x^2 + 6 and g(x) =(x+8/x) . find (g ° f)(–7).

I hope this helps you

f (7)=7^2+6

f (7)=49+6

f (7)=55

g (f (7))=g (55)=55+8/55

g (55)=63/55

Base on the given values above, here is how we found the correct answer. 
At first, what we need to do is to evaluate x first. (g ° f)(–7) is equal to g(f(-7)). So x = -7. So now, plug in the values: 
f (7)=7^2+6
f (7)=49+6
f (7)=55
g (f (7))=g (55)=55+8/55
g (55)=63/55
So the answer would be 63/55.
Hope this answer helps.