Comparing solid shaft with a hollow shaft of same external diameter

A shaft (50mm to 100mm) diameter and 0.7m long is subject to a torque (800 to 1200) Nm. Calculate the shear stress and angle of twist. Take G = 90GPa. Also calculate the same for a hollow shaft with the same external diameter.
Compare the strengths and the twist angles for the solid shaft & the hollow shaft with same external diameter.