GeoGebra Math Practice combines GeoGebra and Graspable Math technology.

A good place to start if this is new to you is the Guided Tutorials, try selecting a plus symbol in this first tutorial.

I do like Graspable Math for enforcing the correct order of operations.

This interface is excellent – steps are recorded as you can see here. Note the video demonstrations also.

Several categories of skills are available, under Enhance your skills, you will find Linear equations, Order of Operations, Algebraic Expressions, and Polynomials. More skills will be added in the next couple of months.

Have a look at this article for teachers, Teachers: Using GeoGebra Math Practice in class.