Мr(Р2О5) = 31*2 + 16*5 = 142
W(P) = 31 * 2 / 142. *100% = 44%
W(O)=16*5 / 142. *100% = 56%

Mr(KNO3) = 39+14+16*3 = 101
W(K) = 39*1 / 101. *100% =39%
W(N) = 14*1 / 101. *100% = 14%
W(O) = 16*3 / 101. *100% = 47%

Mr(Ca3(PO4)2) = 40*3 + 31*2 + 16*8 = 310
W(Ca) = 40*3 / 310. *100% = 39%
W(P) = 31*2 / 310. *100% = 20%
W(O) = 16*8 / 310. *100% = 41%