Let the unknown number be \( x \). According to the problem, the equation can be set up as follows:
\[ \frac{8 + x}{3} = 6 \]
To solve for \( x \), first multiply both sides of the equation by 3 to eliminate the fraction:
\[ 8 + x = 18 \]
Next, subtract 8 from both sides:
\[ x = 18 - 8 \] \[ x = 10 \]
Therefore, the solution for the unknown number is \( x = 10 \).
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