15 : ( 3 12/17 + 2 5/17 ) + (6.2 - 2 3/5) : 4​

1) 3 12/17 + 2 5/17 = 5 17/17 = 6

2) 6,2 - 2 3/5 = 6 2/10 - 2 3/5 = 6 1/5 - 2 3/5 = 31/5 - 13/5 = 18/5

3) 15 : 6 = 15/6 = 5/2 = 2,5

4) 18/5 : 4 = 18/5 : 4/1 = 18/5 * 1/4 = 9/10

5) 2,5 + 9/10 = 2 5/10 + 9/10 = 2 14/10 = 3 4/10 = 3 2/5