Question

pls tell me that in class 9 what i take
computer
commerce
which will help me

Answer 1

commerce will help you in getting good job

Answer 2

Next you need to know why a commerce student join computer course work either for the sake of job or interest in computer. In your opinion nothing is clear as of now so you look for the final word. Again I will ask you that how come you got inspired by computer sciences --by the general references or your commerce skill which impulsed you to explore the computer due to the uniform definition of softskill in any subject. I think this is the genuine explanation which can convince you and your future in the combination of computer sciences and commerce. Therefore the basic insticnt to explore the computer science at higher level is to give anew dimension of comerce. Always keep your basic commerce where you can exploit the computer sciences at max level it is the universal rule before nvestigating anything new. 
Screening of any new subject for you is a crucial job so give ample time to your thought processing and then analyse the modules being offered in computer sciences and align them with your core course in commerce. Hope it will help you to undertand that why you are taking computer sciences. 
Best wishes