To calculate this expression, we will first simplify the expressions within the parentheses:

3,6 - 1 2/3 = 3.6 - 1.67 ≈ 1.93
4 1/15 - 2 7/9 = 4.07 - 2.78 ≈ 1.29

Now, we will multiply these simplified expressions by 2.6:

1.93 2.6 ≈ 5.02
1.29 2.6 ≈ 3.36

Therefore, the final answer is approximately 5.02 : 3.36.