SO2
32g S........32g O2 ....... 64g SO2
x..................y................100g SO2
y=32*100/64=50% O
x = 100-50=50% S
Ca(NO3)2
40g Ca......28g N.........96g O......164g Ca(NO3)2
x............y.................z.............100g Ca(NO3)2
x=40*100/164=24,39% Ca
y=28*100/164=17,07% N
z = 100 - 24,39 - 17,07 = 58,54% O