In the human reproductive process, two kinds of sex cells, or gametes (GAH-meetz), are involved. The male gamete, or sperm, and the female gamete, the egg or ovum, meet in the female's reproductive system.
Since C only binds to G, you have the same amount of C and G, so G is 21 %.
100 % minus 42 % ( 21 % C plus 21 % G=) equals 58 %.
So the other 58 % is made of T and A. Since T only binds to A , the half of the extra 58 % is T and the other half is A. Therefore 29 % is T and 29 % is A
