So, we have an equation with two unknowns. By doing simple math we find concentrations as:
[Acetate-] = 0.37M
[HAcetate] = 0.13 M
Now we can find moles of acetic acid as:
and sodium acetate:
So, to prepare buffer solution we need to take 130 mL of 10M acid and 25.2 g of sodium acetate in a volumetric flask and dilute with DI water up to 500 mL.