To solve this expression, we need to follow the order of operations (PEMDAS/BODMAS).

First, we perform any calculations within parentheses or brackets. However, there are none in this expression.

Next, we evaluate any exponents or powers. Again, there are none in this expression.

Moving on, we perform any multiplication or division from left to right.

-2/5.5 = -0.3636 (rounded to four decimal places)

Next, we add the next fraction: -0.3636 + 8 = 7.6364 (rounded to four decimal places)

Finally, we perform any remaining addition or subtraction from left to right.

7.6364 + 5 = 12.6364 (rounded to four decimal places)

Therefore, the value of the expression -2/5.5/8 + 5/8.3/5 is approximately 12.6364.