Who concluded that in dna adenine levels were equal to thymine levels and cytosine were equal to guanine levels

Chargaff's rules state that DNA from any cell of all organisms should have a 1:1 ratio of pyrimidine and purine bases and, more specifically, that the amount of guanine is equal to cytosine and the amount of adenine is equal to thymine .

wheres the answers ?

we would need to see the picture to answer it