Basically maths use to be much easier to students from CBSE school students than ssc students. And when they change the real benefit is for CBSE students. If you want to improve maths then only thing is you must practice practice and practice. You should first find which type of questions they ask and make a strategy, then you must try to complete chapter by chapter and must even use online resources to understand those. And try to give mocks to have practice of such questions.