Mr((NH4)3PO4) = 14*3 + 1*12 + 31 + 16*4 =149
W(N) = Ar(N) *n / Mr((NH4)3PO4) *100% = 14 *3 / 149. *100% =28%
W(H) = Ar(H) * n / Mr((NH4)3PO4. *100% = 1*12 / 149.* 100% = 8%
W(P) = Ar(P) * n / Mr (NH4)3PO4. *100% = 31 *1 / 149. *100% = 21%
W(O) = Ar(O) * n / Mr ( NH4)3PO4. * 100% = 16*4 / 149. *100% = 43%