Straight-through problem solving in Mathtoys
In some cases it is not possible to work with equivalent steps, but Mathtoys tries to do this when it can. Of course if you solve a math problem by hand it is a good practice to go back and check for errors you may have made along the way.
Solving simultaneous equations
As you work through a problem, Mathtoys shows that each set of equations is equivalent to the set in the previous step and displays the "≡" symbol to indicate this.