-  (- 1/6 – 0,1 – 1/15) : (1/6 – 1/15 + 0,1)/[(0,5 – 1/3 – (- 0,25) – 1/5) : (0,25 – 1/6)] = 25/39;

1). – 1/6 – 0,1 = - 5/30 – 3/30 = - 8/30 = - 4/15;          2). – 4/15 – 1/15 = - 5/15 = - 1/3;

3). 1/6 – 1/15 = 5/30 – 2/30 = 3/30 = 1/10;                  4). 1/10 + 0,1 = 2/10 = 1/5;

5). – (- 1/3) : 1/5 = 1/3 * 5 = 5/3;                                    6). 0,5 – 1/3 = 3/6 – 2/6 = 1/6;

7). 1/6 – (- 0,25) = 2/12 + 3/12 = 5/12;                          8). 5/12 – 1/5 = 25/60 – 12/60 = 13/60;

9). 0,25 – 1/6 = 3/12 – 2/12 = 1/12;                             10). 13/60 : 1/12 = 13/60 * 12 = 13/5;

11). 5/3 : 13/5  =  5/3 * 5/13 = 25/39;