Please visit http://topinmath.com/. This is a step by step math solution for school students. It can solve almost any problem giving step by step textbook solution. It can also generate problems (on the fly) with solution, with answer and without answer. It will keep generating new problems and rarely repeats any problem. The algorithm to generate human method to solve mathematical problems is very complicated and challenging.
Please also visit www.gstexplore.com. You can ask any question regarding GST in plain English and it gives relevant answer with section and rule number.