How to solve

Problem $2(12$ points$)$

There are different designs for mountain bike suspension system. Allsop mountain bike as shown in the picture is a softride mountain bike. If a player's weight cannot exceed $350$lb and the diameters of pin A and pin $B$ are both $7\mathrm{.}5$ mm $.$ Pin A and $B$ are the same material and both are double shear. Determine the material's shear failure stress ${}_{\text{f}\text{a}\text{i}\text{l}}$ F$.$S$.=2$