If the number of adenine nitrogenous base in a given DNA segment is...

According to Chargaff's rule for a double-stranded DNA molecule, the number of adenine bases is equal to the number of thymine bases, and the number of guanine bases is equal to the number of cytosine bases.

Given, Adenine (A$) = 25$

Therefore, Thymine (T$) = 25$

Given, Guanine (G$) = 45$

Therefore, Cytosine (C$) = 45$

Total number of nucleotides = $A + T + G + C$

Total number of nucleotides = $25 + 25 + 45 + 45 = 140$

Answer: 140