A 75.00 g a sample of a substance is analyzed and found to consist of 32.73 g phosphorus and 42.7 g oxygen. calculate the percent composition of this substance.

The sum of the parts in this problem is slightly bigger than the total

32.73 + 42.7 = 75.43

Then the percentage composition is not going to be 100% exact but you can calculate some approximation in the following way

% = Part x 100/Total

phosphorous Part = 32.73 g

oxygen Part = 42.7 g

Total = 75.00 g

% phosphorous = 32.73 g x 100 / 75.00 g = 43.64% phosphorous

% oxygen = 42.7 g x 100 / 75.00 g = 56.93 % oxygen