A car is moving along a straight line OP as shown in the figure. It moves from O to P in 18 s and returns from P to Q in 6 s. Which of the following statements is not correct regarding the motion of the car
A : The average speed of the car in going from O to P and come back to Q is 20m
B : The average velocity of the car in going from O to P and come back to Q is 15m