simplify this expression

I think your "4x2" is meant to be read "four times x squared"? Anyway, start from the most embedded bracket and gradually expand it all out. So to start with, -(9x - 7) would become -9x + 7. Since the minus at the front means "multiply everything in this bracket by minus one". Then just try to work through it in that sequence. Finally, at the end, make sure that there are only three terms: a number, a term in x, and a term in x squared. Good luc - get back to me if you are still struggling.