What is the mass number of a neutral atom that contains 3 electrons and 4 neutrons

If its a neutral atom, and has 3 electrons,
has 3 protons.
protons and neutrons have each 1mass number

so, 3+4=7 mass number of that atom

since it is a neutral atom, it has the same number of protons as electrons, which is 3
the mass of the atom is defined by neutrons+protons,
therefore
3+4 = 7

This is lithium.

neutral atom with 3 electrons must have 3 protons, (3 x -ve and 3 x +ve)

3 protons and 4 neutrons = weight of 7

mass number is 7

ps. this is not a maths question but I will give it to you any way.

since the atom is neutral it must contain 3 protons 3 protons and 4 neutrons means this atom has a weight of 7

7