var expr = new Expression('x');
expr = expr.subtract(3);
expr = expr.add('x');

console.log(expr.toString());

var eq = new Equation(expr, 4);

console.log(eq.toString());

var x = eq.solveFor('x');

console.log('x = ' + x.toString());

git clone https://github.com/divyun/algebra.js.git
cd algebra.js

var algebra = require('./algebra');