A $2\mathrm{.}15-$kN$$m torque T is applied to the solid cylinder shown to the right. $($a$)$ Determine the maximum shearing stress. $($b$)$ Determine the percent of the torque carried by the inner $25-$mm$-$diameter core. $[87\mathrm{.}610^6$ Pa; THIS IS THE CORRECT ANSWER $($I need the work to get that$)$