Suppose you see a crescent Moon. How do you know if it is waxing or waning?

waxing is in the evening and waning is in the morning if you cant see the moon in the evening it is waning if you can see it in the evening it is waxing

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