First find g(2) by plugging 2 in for every x value in the equation g(x)=x^2-6X-7
g(2)=(2)^2-6(2)-7
g(2)=4-12-7
g(2)=-15
Then, we can find f(g(2)) because we know g(2)=-15. So we're really looking for f(-15)
f(-15)=x+8
f(-15)=(-15)+8
f(-15)= -7
Hope this helps