How many additive cosets exist for the ideal I in the subring R?

[e179285]

Let R be the subring {x + yi : x, y in 2Z} of C, and
let I be the ideal {x + yi : x,y in 2Z}of R.
How many additive cosets has I in R? List them clearly.

I know definition of ideal but ı don't know how to write in set is that question describe.Please help :)

 

[micromass]

Did you make a typo?? The way you wrote it implies that I=R.