which of the following is not a layer of the atmosphere?
a. lithosphere
b. exosphere
c. thermosphere
d. mesosphereupdate: answer- exosphere

The layer that doesn't exist at all is the lithosphere because the very last level of the entire atmosphere is the exosphere.

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

Answer it was we, the the whole people, who formed the union. and we formed it, not to give the blessings of liberty, but to secure them: not to the half of ourselves and the half of our posterity, but to the whole people- women as well as men.