You are working as a Structural EIT for YYC Engineering. You have been tasked to determine the maximum allowable torque that can be applied to the assembly shown below. A hollow steel shaft $($ABC$)(\backslash (\backslash$mathrm$\{$G$\}=75\backslash$mathrm$\{$GPa$\}\backslash ))$ is perfectly bonded $($region BC $)$ to a solid aluminium shaft $($BCD$)\backslash ((\backslash$mathrm$\{$G$\}=25\backslash$mathrm$\{$GPa$\})\backslash ).$ Determine the maximum torque $\backslash ($ T $\backslash )$ that can be applied at the end D if the maximum allowable shear stress for steel is $150$ MPa and for aluminum is $60$ MPa $.$ Also, determine the angle of twist at C and at D for this maximum torque.