1) 1 2/3 - 3 1/5 = 5/3 - 16/5 =(5 × 5 - 16 × 3)/15 = 25/15 - 48/15 = - 23/15 = - 1 8/15
2)4 3/5: (-1 8/15)=23/5 : ( - 23/15) = 23/5 × ( - 15/23) =-345/115= - 3
3)- 3 + 1 3/8 = - 3 + 11/8 =(-3 × 8 + 11 × 1)/8 = -24/8 + 11/8 = - 13/8 = - 1 5/8
ответ - 1 5/8