1. The problem statement, all variables and given/known data The question is asking for the internal forces at E, but I get stuck solving the external reactions. After that, I can do it, and have, using electronically generated results. I just get stuck solving the system of equations I get after doing the determinant equations. We ignore the reactions at E. Those will be applied in the next step, where I find the internal forces there. I just drew them in to help me remember where they are, and to visualize the problem. The moment occurring between O and C has a magnitude of 300 kNm, and acts in the k direction. 2. Relevant equations [tex] \Sigma M_x = A_z + 0.4B_z - 0.75C_y - 5 = 0[/tex] [tex] \Sigma M_y = A_z + 0.75C_x = 0[/tex] [tex] \Sigma M_z = -A_y - 0.4B_x - 10 = 0[/tex] [tex] \Sigma F_x = C_x + B_x + +7 = 0[/tex] [tex] \Sigma F_y = C_y + A_y - 12 = 0[/tex] [tex] \Sigma F_z = B_z + A_z - 5 = 0[/tex] 3. The attempt at a solution I tried it for two different unknowns, and both times it didn't work. Sorry for the poor images; I did the work in pencil, and it wouldn't scan very well. Here are the real answers, and when I put my equations into a computer, it solves them and gets these. As such, I know my equations are correct. My problem just pops up when I try and solve for each unknown. If anyone could help me see where I went wrong, I'd be very grateful to them.