Consider the following set of equations...
3x + y + z ? u = 9
13x + 8y + 6z ? 7u + 3 = 0
14x + 10y + 6z ? 7u = 4
7x + 4y + 3z ? 3u = 5
Use Solver in excel to find a solution to this set of equations. It is up to you to determine the necessary constraints on such a system.