how to solve 2(sin2x) - 2(sinx) ?

This is not a complete question.

And you haven't shown your attempt.

Because I do not know how to even start it.

If you're being given such a question as homework, it means that you should be able to do it and that it's only practice. Review your notes, your books, there should be examples. Apply the same concept.

You can't "solve" the equation as written - it needs an equal sign somewhere. Maybe you meant to write 2sin(2x)= 2sin(x), or perhaps 2sin(2x)-2sin(x) = 0?

Here's a hint though: consider the identity for sin(2x) - substitute that in and it should simplify things nicely.