4. (10 points) Three large plates are separated by thin layers of ethylene glycol(viscosity = 1.99 x 10-² N-s/m²) and water (viscosity = 1.00 x 10-³ N·s/m²), as shown in the figure below. The top plate moves to the right at 2 m/s. At what speed (in units of m/s) and in what direction must the bottom plate be moved to hold the center plate stationary? Assume linear velocity profiles in the fluids.

Fig: 1

Fig: 2