Hey there,
So. . .I saw that you chose a large dog. So if a large dog's expression would be

. So if that would be that. . What would be a Humans, and determining his birth and age years. So. . This adult would be 75 years old and he is

. The difference between those two ages is the one is 2 and the other is 8. So your answer could be 6.
~Jurgen