108:а=9

To solve the equation \( 108 : a = 9 \), we can interpret the colon (:) as division. So, the equation can be rewritten as:

\[ \frac{108}{a} = 9 \]

To isolate \( a \), we can multiply both sides by \( a \) to eliminate the denominator:

\[ 108 = 9a \]

Next, we can solve for \( a \) by dividing both sides of the equation by 9:

\[ a = \frac{108}{9} = 12 \]

Thus, the value of \( a \) is \( 12 \).