Python

solve(v, q). Solve the equation q for the variable v, and return a new equation in which v appears alone on the left side of the equal sign. For example, if you call solve like this: solve('x', ((('m', '*', 'x'), '+', 'b'), '=', 'y')) then it will return this: ('x', '=', (('y', '-', 'b'), '/', 'm')) The function solve really just sets things up for the function solving, which does all the work. If v is inside the left side of q, then call solving with v and q. If v is inside the right side of q, then call solving with v and a new equation like q, but with its 2 left and right sides reversed. In either case, return the result of calling solving. If v is not inside q at all, then return None. Can't figure out how to write it properly. I've got this, but it doesn't quite work.

def solve(v, q): if v == left(q): return solving(v, q) elif v == right(q): return solving(v, reversed(q)) else: return None