3/5:(7/60):(-3 11/15)*1 2/3=

3/5 : (7/60) : (-3 11/15) * 1 2/3 = - 2 29/98

1) 3/5 : 7/60 = 3/5 * 60/7 = (3*12)/(1*7) = 36/7
2) 36/7 : (-3 11/15) = 36/7 : (-56/15) = 36/7 * (-15/56) = - (9*15)/(7*14) = - 135/98 
3)  - 135/98 * 1 2/3 = - 135/98 * 5/3 = - (45*5)/(98*1) = - 225/98 = - 2 29/98

Пояснения:
3 целых 11/15 = (3*15+11)/15 = 56/15
1 целая 2/3 = (1*3+2)/3 = 5/3