A 10lb particle has forces of F1​=(3i+5j)lb and F2​=(−7i+9j)lb acting on it. Determine the acceleration of the particle.
(A) (−0.4i+1.4j)ft/s²
(B) (−4i+4j)ft/s²
(C) (−12.9i+12.9j)ft/s²
(D) (13i+4j)ft/s²