Dear forum, I'm new here (living in Arizona). I am stuck getting to derive this: F1−F2−F3 = 0, (2.1) F1c1−F2c2−F3c3 = 0, (2.2) F1z1−F2z2−F3z3 = 0. (2.3) Where the only unknowns are F2 and F3. The text book states that F1, F2 and F3 can be eliminated to get: c1z3 −c1z2+c2z1 −c2z3 −c3z1 +c2z2 = 0 (2.4) Can anyone help the step-by-step solution in getting from 2.1 to 2.3 to get 2.4? This is a problem of chemical process data balancing (reconciliation), but without the understanding on how to derive the mathematics, one will be stuck with future similar problems. Thank you for your help, forum!