Question

A single strand of DNA helix consists of 100 nitrogenous base pairs. If 36 of the bases are adenine and 24 are cytosine, how many should be thymine on the complementary strand?

Answer 1

Chargaffs rule; 

A=T 
C=G 

Therefore; 
36 Adenine = 36 Thymine 
24 Cytosine = 24 Guanine 

This rule arises because of the complementary base pairing found in DNA and RNA