A circular steel shaft 6 feet in length is subjected to a twisting moment of 5000 lbs?

A circular steel shaft 6 feet in length is subjected to a twisting moment of 5000 lbs.For this load the shearing stress was measured to be 8000 lbs. per square inch and the angle of twist was 1.5 degrees . If the maximum shear stress is not to exceed 9000 lbs. per square inch and the allowable angle of twist is not to be greater than 2 degrees compute the allowable torque for this circular shaft if tha angle of twist and shearing stress are proportional to the torque as well.