-6,4:(-8)=

To solve the expression \(-6,4:(-8)\), we need to clarify what the notation means, particularly the comma and the colon.

Assuming "-6,4" represents the decimal number -6.4 and the colon ":" denotes division, we can rewrite the expression as:

\[ -6.4 \div -8 \]

Now, dividing \( -6.4 \) by \( -8 \):

\[ -6.4 \div -8 = 0.8 \]

So, \(-6.4 : -8 = 0.8\).