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 + v₂/2)
b. (/2v₁v₂/v₁ + v₂)
c. (/2v₁v₂/v₁ - v₂)
d. (/v₁ - v₂/2)