Please answer and explain:

knowing that f(n) and g(n) are each O(h(n)) for some function h, show rigorously (using the definition of O()) that f (n) + g(n) is also O(g(n)).

Remember: f(n) is O(h(n)) if there exist c > 0 and n0 0 such that for all n n0, f(n) ch(n).