To add these mixed numbers, we first need to convert them to improper fractions:

-4 3/4 = -19/4
-3 5/6 = -23/6
1 3/8 = 11/8

Now we can add the improper fractions:

-19/4 + (-23/6) + 11/8

To add fractions with different denominators, we need to find a common denominator. The least common multiple of 4, 6, and 8 is 24.

-19/4 = -114/24
-23/6 = -92/24
11/8 = 33/24

Now we can add:

-114/24 + (-92/24) + 33/24 = -173/24

Converting this improper fraction back to a mixed number:

-173/24 = -7 5/24

So, -4 3/4 +(-3 5/6)+1 3/8 = -7 5/24.