[Pupate]

I have been assigned this problem for homework, and although I'm usually good with problems regarding molarity, this one has me stumped. If anyone could help me out by giving me a hint or something, I would really appreciate it. Here is the problem:

A 6M HCl (aq) solution is quite concentrated. This solution can be assumed to have a density of 1.08g/ mL and to be roughly 20% HCl by mass. Find the 'molarity' of the water in a 6M HCl (aq) solution; that is find the moles of H2O per liter of solution.

I just have no idea where to start. I tried by multiplying the 6M HCl by HCl's molar mass to get it in grams/liter and then multiplying by .80 to get the mass of water in the solution of HCl, but I have no idea where to go after that. I'm stuck. Any help would be appreciated!

[Borek]

What is mass of 1L of this solution?

What is mass of HCl in 1L of this solution?

What is mass of water in 1L?

What is definition of molarity?