Gravimetric ysis millimoles?

i'm taking a chemistry lab. we did a gravimetric ysis lab. made a stock solution (10 mL of H2SO4 and H2O) that has a concentration of 0.6M. We added 25 mL of stock solution to a clean flask and diluted it with distilled water to make 0.15M solution called final solution. We then added 5.0 mL BaCl2 in a clean beaker. We then put 5.00 mL of final solution in a separate beaker and added 5.0mL of 1.0M HCl to the final solution. We heated both beakers until near boiling. Then we poured the BaCl2 in the H2SO4 solution to form a precipitated. We filtered it through some filter paper to separate the precipitate. It dried for a week and then we weighed it. It was 0. 185 g. I calculated the millimoles of BaSO4 to be 7.97x 10^-7 (not sure it's correct though.). How would I find the millimoles of H2SO4 that reacted? The volume of the final solution (mL)? And the molarity of final solution? I don't necessarily want the answers, I just want to know how to solve the problem. Thanks.