Three astronauts, propelled by jet backpacks, push and guide a 149 kg asteroid toward a processing dock, exerting the forces shown in the figure, with F1 = 28 N, F2 = 59 N, F3 = 41 N, θ1 = 30°, and θ3 = 60°. What is the (a) magnitude and (b) angle (measured relative to the positive direction of the x axis in the range of (-180°, 180°]) of the asteroid's acceleration?