20,8:(12-11,36)-8:12,5

Let's break down the expression step by step.

The expression is:

\[ 20.8 : (12 - 11.36) - 8 : 12.5 \]

1. Calculate \( 12 - 11.36 \): \[ 12 - 11.36 = 0.64 \]

2. Now substitute this back into the expression: \[ 20.8 : 0.64 - 8 : 12.5 \]

3. Perform the division:

   • \( 20.8 : 0.64 = \frac{20.8}{0.64} = 32.5 \)
   • \( 8 : 12.5 = \frac{8}{12.5} = 0.64 \)

4. Substitute back into the expression: \[ 32.5 - 0.64 \]

5. Now perform the subtraction: \[ 32.5 - 0.64 = 31.86 \]

So, the result of the expression is: \[ \boxed{31.86} \]