Molecular basis of inheritance

In three turns of ds DNA, there will be 30 base pairs as, there is 10 base pair in one turn so, i.e 60 nucleotides out of which 20 % is is thymine , 20% of 60= 12 nucleotides are thymine , and from chargaffs rule we know no of Thymine =number of adenine and number of guanine=number of cytosine ,as Thymine and adenine are bonded by double H bond, no of H bond =122=24, and remaiming nucleotides are 60-24=36, in which 18 are guanine and cytosine each, guanine and cytosine are bonded by triple Hydrogen bond, so 183=54,now total number of H bonds =24+54=78. Hope you got your answer.

48 H Bonds Between AT 114 H bonds Between GC