An even number minus an even number

An even number minus an even number will always equal an even number.

If the differences between the group means is large relative to the amount of variability in the scores, the group differences are probably significant. If, however, there is a lot of variability in the scores, then the difference between (or among) the group means will not seem so large, a non-significant difference.

So to summarize, it depends on the group. As there is no shown group, I can't determine what it would be.