$1\mathrm{.}7-9$ What is the maximum possible value of the clamping force $C$ in the jaws of the pliers shown in the figure if $a=3\mathrm{.}75$ in$.,b=1\mathrm{.}60in.,$ and the ultimate shear stress in the $0\mathrm{.}20-$in$.$ diameter pin is $50$ ksi $?$

What is the maximum permissible value of the applied load $P$ if a factor of safety of $3\mathrm{.}0$ with respect to failure of the pin is to be maintained?

$($ans$.$: P$\_$allow$=157$ lbf$)$