Given the functions:
f(x)= {(3,5), (2,4), (1,7)}
h(x)= {(3,2), (4,3), (1,6)}
g(x)= sqrt(x-3)
k(x)= x^2=5

determine
1) f(h(3))
2) g(k(x))
3) g(k(7))
4) k(g(x))