What is meant when the symbol C-12 is used?

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: i dont know the answer but this might

explanation:

l

it is b that is the answer.

explanation:

0.07 g/cm³

1.37 g/cm³