M(H3PO4)= 3+31+64=98 W(H)= 3\98 *100%= 3% W(P)= 31\98*100%=32% W(O)=64\98*100%=65% M( NaOH)=23+16+1=40 w(Na)=23\40*100%=58% w(o)=16\40*100%=40% w(H)=1\40*100=2