what is the pH and pOH of a soution with a volume of 5.4 that contains 15 grams of HCl and 25 grams of nitric acid

Answer 1

volume of 5.4 WHAT? liters?
15g HCl = how many mols? mol = g/molar mass.
25 g HNO3 = how many mols. g/molar mass = ?

Add mols H from HCl to mols H from HNO3 to find total H^+, then molarity = M = moles H^+/L solution. (L soln may be the 5.4 you wrote with no units.)
Then pH = -log(H^+) to find pH and
pH + pOH = pKw = 14 to find pOH.