To solve this expression, we follow the order of operations (parentheses, multiplication and division, addition and subtraction) while also considering the specific comma decimal notation used:

Start by evaluating the expression within the parentheses:
(17,65 - 9,25) 2,5 - 3,9 0,4
= (8,4) 2,5 - 3,9 0,4
= 21,0 - 1,56
= 19,44

Next, we divide the result by 2,43:
19,44 : 2,43
≈ 7,99177

Continuing with the remaining part of the expression:
15,96 : 5,7 0,5 + (13,25 - 8,35) 2,5
≈ 2,8 0,5 + 4,90 2,5
= 1,4 + 12,25
= 13,65

Finally, we add the results from step 2 and step 3:
7,99177 + 13,65
≈ 21,64177

Therefore, the final result of the expression is approximately 21,64177.