1. 4 8/15 : 2 2/3 = 68/15 : 8/3 = 68/15 * 3/8 = 17/5 * 1/2 = 17/10 = 1 7/10 = 1,7
2. 2 3/5 : (5/9 + 5,3) = 2 3/5 : (5/9 + 53/10) = 2 3/5 : (50/90 + 477/90) = 2 3/5 : 527/90 = 13/5 * 90/527 = 13/1 * 18/527 = 234/527
3. (3,5 - 1 1/3) : 2/13 = (35/10 - 4/3) : 2/13 = (105/30 - 40/30) : 2/13 = 65/30 : 2/13 = 13/6 * 13/2 = 169/12 = 14 1/12