The answer to this question would be 65% oxygen, 18% carbon, 10% hydrogen, 3% Nitrogen, 1.5% calsium, 1% phosphorus, 0.25% sulphour and 1.25% other elements. These values are the approximate contents of different elements in a human being.

An example: If the person has a mass of 30 kilograms, (30/100)*65=19.5 Kg will be oxygen.