1. The problem statement, all variables and given/known data in this diagram , we could see two forces acted to left , one force acted to right , total of two forces acting to left = force acting to right . 2. Relevant equations 3. The attempt at a solution i'm wondering if the total of two forces on the left are not the same with the force on the right , then , how to do the question ? We know that tau = P/ A , tau = stress , P = force . let's say one of the force is 30kN to left , another one is 40kN to left , total is 70kN to the left , but on the right , the force is 60kN to right ... so , the shear stress = 10kN to right divided by area ?