The atomic number of an isotope is the number of protons it contains, whereas the mass number is the total mass of the nucleus, which is the combined number of protons and neutrons in the nucleus. To find the number of neutrons, you must therefore subtract the atomic number of the isotope from the mass number of the isotope. 
<span>In the above example, the atomic number is 8 and the mass number is 18. This isotope is known as O18. The number of neutrons in the isotope is: Mass number - Atomic number = Number of neutrons
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Answer:
G=21 %
T= 29 %
A= 29 %
Explanation:
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
 
        
             
        
        
        
It transfers from being to being, from the sun, where it starts, to every other being after.
Hope this helped.