The sum of neutrons would be 55. (: I hope this helps. because if you minus the mass number by the atomic number which is always equivalent to the number of protons, you get the amount of neutrons. The amount of protons and neutrons always add up to the mass number.
I read this story and so I can say its answer should be 4 (She has gained a deeper understanding of her daughter).
The answer opinion because it is personal to self
