1)
68/15 : 8/3 = 68/15 * 3/8= 17/5 * 1/2 = 17/10=1,7
2)
13/5 : (5/9+5 3/10 )
1)5/9+5 3/10 = 5 50+27/90 =5 77/90=527/90
2) 13/5 : 527/90 = 13/5 * 90/527 = 13/1 * 18/527 = 234/527
3)
(3 1/2 - 1 1/3) : 2/13=
1) 3 3/6 - 1 2/6 = 2 1/6=13/6
2)13/6 : 2/13 = 13/6 * 13/2 = 169/12