A person traveling on a straight line without changing direction moves from uniform velocity v1 for distance half the next half distance he covers with uniform speed v2 the average speed is: A) v₁ + v₂ B) 2v₁v₂ / (v₁ + v₂) C) v₁v₂ / (v₁ + v₂) D) v₁ - v₂