answer:f(g(x)) must have a degree of 6, because it will produce the term with the greatest exponent of the polynomial. Because f(x) is a degree 2 polynomial, we can write that f(x)=bx^2+cx+d. The term with the greatest exponent in f(g(x)) comes from taking bx^2 or b(g(x))^2. Let g(x)=a_{n}x^{n}+a_{n-1}x^{n-1}+...+a_{2}x^{2}+a_{1}x^{1}+a_0. Then, the highest degree term of f(g(x)) is b(a_nx^n)^2, which equals ba_{n}^2x^{2n}. Since the degree of h is 6, we have 2n=6, so n=3. Therefore, the degree of g is boxed{3}.

answer:Since g(5) = 5+3=8 and f(5) = 5^2 - 2(5) + 5 = 25-10+5 = 20, we have f(g(5)) -g(f(5)) = f(8) - g(20) = 8^2 - 2(8) + 5 - (20+3) = 64 - 16 + 5 - 23 = boxed{30}.

answer:Let a be Andrew's age now and g be his grandfather's age now. We are looking for the value of a. We can set up a system of two equations to represent the given information, as follows: begin{align*} g &= 12a g-a &= 55 end{align*} In particular, the second equation represents the grandfather's age a years ago, when Andrew was born. To solve for a, we need to eliminate g from the equations above. Substituting the first equation into the second to eliminate g, we get that 12a-a=55 or a=5. Thus, Andrew is boxed{5} years old now.

answer:We cube both sides to eliminate the cube root: 3-frac{1}{x}=-64. Simplifying gives frac{1}{x}=67 and taking the reciprocal of both sides gives boxed{x=frac{1}{67}}.