To simplify this expression, we will first combine like terms:

-4 2/5 - 2,7y + 3 1/2y - 6,4

Now we will convert the mixed numbers to improper fractions:

-22/5 - 27/10y + 7/2y - 64/10

Next, we will combine the y terms:

-22/5 - 27/10y + 7/2y - 64/10 = -22/5 - (27/10 - 7/2)y - 64/10

Now we will simplify the y terms:

-22/5 - (27/10 - 7/2)y - 64/10 = -22/5 - (-13/10)y - 64/10 = -22/5 + 13/10y - 64/10

Finally, we will convert back to mixed number form if necessary:

-22/5 + 13/10y - 64/10 = -4 2/5 + 1 3/10y - 6 2/5

Therefore, the simplified expression is -4 2/5 + 1 3/10y - 6 2/5.