What is the twist at the end of the shaft shown in Fig. P. 14.30 (the sleeve and inside core are made of different materials and are entirely fastened together), when $G$ for the sieeve is $1 \times 10^{11} \mathrm{~Pa}$ and $G$ for the core is $7 \times 10^{16} \mathrm{~Pa}$ ? Sce result from Problem 14,62.