The answer can be derived from the grey circle.
if u take it as z in the units place
z + z + z = z
Only 2 numbers can give you such a result either 0 or 5.
Since its addition and the final sum cannot be 000.
Hence its 555.
As all three numbers are same to find the others we can do the following;
555 / 3 = 185
HenceBlue = 1;Red = 8 and;Grey = 5