To solve the proportion \( \frac{x}{5} = \frac{8}{9} \), you can use cross-multiplication.
Cross-multiplying gives:
\[ x \cdot 9 = 5 \cdot 8 \]
This simplifies to:
\[ 9x = 40 \]
Now, divide both sides by \( 9 \) to solve for \( x \):
\[ x = \frac{40}{9} \]
So, the solution is:
\[ x = \frac{40}{9} \]