Will I be able to do both business and economics or is it better to do only one of them please help.
You can do both. Unless you're really sure what you want don't limit yourself too much though
If you want to do medicine you'd probably be better off with at least 2 sciences and one business subject, as opposed to 2 businesses and 1 science. Any particular reason why you don't want to do Biology/Physics/Chemistry?
If you love Business & Economics and don't want to do Physics, then there's no reason why you shouldn't choose them. They're both great subjects, and I'm personally jealous of people who get to pick them :P