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