The given fractions are:
\[
\frac{8}{27}, \quad \frac{4}{27}, \quad \text{and} \quad \frac{6}{27}.
\]
Step 2: Add the numerators
Since all the fractions have the same denominator, we can add the numerators directly:
\[
8 + 4 + 6 = 18.
\]
Step 3: Write the sum as a fraction
The sum of the numerators is 18, and the common denominator is 27. Thus, the sum of the fractions is:
\[
\frac{18}{27}.
\]
Step 4: Simplify the fraction
The fraction \(\frac{18}{27}\) can be simplified by dividing both the numerator and the denominator by 9:
\[
\frac{18 \div 9}{27 \div 9} = \frac{2}{3}.
\]