How to start with solving sets of equations? What are equivalence principles?[br]Brooms can solve the problem... [br]Because isn't the crossing of two brooms a different thing than the solution of a set of equations? And if I hold a third broom so that it goes through the same point I might is well remove one of the first two. [br][list][*]Why should I take a third broom?[/*][*]How shoulf I hold it to define more easily the crossing point?[/*][/list]