I don't know where to start. Could someone help?

 

A 7.67 M solution of an acid, HX, has a density of 1.192 g/mL. THe acid, HX, has a molar mass of 53.00 g/mol. Determine the concentration of this solution in molality, Xhx(mole fraction of HX), and %w/w(percent by mass). The solvent in this solution is water, H2O.

Do not confuse molaRity with MolaLity. Here, you have both.

 

Check the density of water, the rest should fall into place.

 

Cheers,

 

O3

here's a useful page from wikipedia. It lists all of the concentration measures you referred to

Isn't [math]b=\frac{n}{m}[/math] used here?

A formula is useless unless you define the terms.