45. Solving a chemistry problem

428. After dissolving and treating 0.9860 g of the fertilizer, an aqueous solution containing HPO42- was obtained, which was quantitatively precipitated by adding 40.00 ml of a 0.2040 M AgNO3 solution. Titration of excess Ag in the filtrate and washings after separation of the precipitate required 8.72 ml of 0.1170 M KSCN solution. Calculate the percentage of P2O5 in the sample.