(a) A thin wire is in the shape of a parabola y = 4 x from (-1, 3) to (2,0). If p(x,y) = x(4 y) is the variable mass density of the wire, then find the mass of the wire. (b) State Green's theorem. Use Green's theorem to find the work done by the variable force field F(x, y) = (e* + 2y)i + (e x) j on a particle that travels along the closed path x2 + y = 9 in the anti-clock wise direction.