Nitrogen (n) atomic number = atomic mass = number of protons = number of neutrons = number of electrons = number of electrons in the valence shell:

Nitrogen, Periodic abbreviation= N
Atomic Number: 7, as it has 7 protons
Atomic Mass: 14.007, so around 7 protons and 7 neutrons depending on isotope type
# Protons: 7
# Neutrons: 7
# Electrons: 7, usually, but not always, equal to # of Protons
Valence Electrons: 5, as with 7 electrons total, 2 would fill the first valence shell, leaving 5 in the valence, or outermost, shell.

the catch is that the top numbers are atomic masses the bottom numbers are the numbers of protons and electrons in an uncharged atom. they are the number of that atoms as you would find them on the periodic table. further, the numbers on the left are used to determine the missing numbers on the right

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer