The magnitude of the torque applied to gear $\mathrm{C}$ can be determined from the torque acting on gear $\mathrm{B}$ and the gear ratio.

While gear diameters are not explicitly stated here, the number of teeth on each gear is proportional to the gear's diameter. Hence, the gear ratio is found from the ratio of gear teeth. The magnitude of the torque applied to gear $\mathrm{C}$ is thus:

$$\begin{gathered} {\mathrm{T}}_{\mathrm{C}}={\mathrm{T}}_{\mathrm{B}}\frac{{\mathrm{N}}_{\mathrm{C}}}{{\mathrm{N}}_{\mathrm{B}}}=(43,768 \mathrm{lb}-\mathrm{ft})\frac{72 \mathrm{teeth}}{24 \mathrm{teeth}} \\ =131.303 \mathrm{lb}-\mathrm{ft} \end{gathered}$$