To simplify the given expression, we will first find the sum of each set of fractions separately, and then add the results together.

(-5/8 + (-2/6)):
To add these fractions, we need to find a common denominator. The lowest common multiple of 8 and 6 is 24.
So, we rewrite the fractions with denominator 24:
(-15/24) + (-8/24) = -23/24

(-4 7/8 + (-3 2/5)):
First, convert the mixed numbers to improper fractions:
-4 7/8 = -4(8/8) + 7/8 = -32/8 + 7/8 = -25/8
-3 2/5 = -3(5/5) + 2/5 = -15/5 + 2/5 = -13/5

Now we add the fractions:
(-25/8) + (-13/5)
To find a common denominator, we multiply the denominators: 8*5 = 40.
Rewriting the fractions with denominator 40:
(-125/40) + (-104/40) = -229/40

To find the final sum:
-23/24 + (-229/40)
To add these fractions, we need to find a common denominator. The lowest common multiple of 24 and 40 is 120.
So, we rewrite the fractions with denominator 120:
-2875/120 + (-6876/120)
Adding them together, we get:
= -9751/120

Therefore, the simplified expression is -9751/120.