By considering the manipulation rules of algebra as productions, problems involving the simplification of algebraic expressions can be solved in the context of a production system. Identify a set of algebraic productions that allow the equation $3 /(2 x-1)=6 /(3 x+1)$ to be reduced to the form $x=3 .$ What are some general rules (that is, heuristic rules) used when performing such algebraic simplifications?