How do I solve these questions? (please show work and provideanswers)

Fertilizers show the different percentage of components in the fertilizer by printing a NPK rating on the bag. This strands for nitrogen - phosphorus - potassium. A rating of 13 - 10 - 10 contains 13% nitrogen by mass, 10% phosphorus (actually PO), and 10% potassium (actually KO) by mass. A fertilizer company made a fertilizer claiming a rating 15 -0 -0. The nitrogen was contained as ammonium sulfate ((NH4)SO). 9. Calculate the concentration of the (NH4)SO4 solution: LESCO TURF FERTILIZER 10. How many moles of SO4 are in 50 mL of the (NH)SO solution? 15-5-10 A student tested the percentage of N in the fertilizer by dissolving 100 grams of fertilizer in 1 L of distilled water. 50 mL of the solution was then reacted with an excess of 1 mol/L barium chloride (BaCl2) solution. The equation for the reaction is: BaCl(20) + (NH4)SO4(30) BaSO4(s) + 2 NHCl (30) The solid barium sulfate was then filtered, dried and weighed. Its mass was 6.5 grams. 8. Calculate the mass of (NH4)SO4 in 100 grams of fertilizer: LESO 11. What mass of BaSO4 would be expected to be produced in the reaction? 12. Was the fertilizer company correct in saying its fertilizer contained 15%N? Give reasons for your answer: