Gear B supplies 15 kW of power, while gears A , C, and D withdraw 6 kW, 4 kW, and 5 kW,...

Gear B supplies 15 kW of power, while gears A , C, and D withdraw 6 kW, 4 kW, and 5 kW, respectively. If the shaft is made of steel with the allowable shear stress of τ_allow = 75 MPa, and the relative angle of twist between any two gears cannot exceed 0.05 rad, determine the required minimum diameter d of the shaft to the nearest millimeter. The shaft is rotating at 600 rpm.