Help please!

A motorcycle traveling on the highway at a speed of 80.0 mi/hr passes a car traveling at a speed of 60.0 mi/hr. From the point of view (or frame of reference) of a passenger in the car, what is the velocity of the motorcycle? Write the equation in the form that I have gone over, with subscripts of: m = motorcycle rider, c = car passenger, e = earth, and assume the forward direction is positive.

From the frame of reference of the motorcycle rider, what is the velocity of the car passenger?