Find fq, the vertical force that pier q exerts on the right end of the bridge.

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View the entire bridge as the system, and find the torque about a pivot chosen to eliminate the torque from one of the unknowns
Find the sum of the torques ∑ τ Q about the right pier Q of the bridge. Remember that counterclockwise torque is positive
∑τQ - 2MgL− 3FpL

The sum of the torques is zero

FP = 2/3 Mg

Ibelieve your answer is b.hope this : )