Rachel and Sarah are on a bus travelling at 5 mph past John who is standing on the sidewalk. Rachel then throws a ball
forward to Sarah at a speed of 20 mph in the frame of reference of the bus. From the point of view of John, the ball is traveling
with a speed of
x
Select one:
a. 20 mph
b. 25 mph
c. 15 mph
d. 5 mph
