Does y plus -y 0 show the inverse property of addition?

Answer 1

Yes, that's what we mean by "-y" or "negative y" -- it's the additive inverse of y.

-y is defined as the number which, when added to y, gives zero.

y + -y = 0

(Zero, in turn, is defined as the additive identity -- the number which, when added to x, gives x.)