(-10 - 9 3/4) + 3 1/6 - (4 1/4 - 1 7/8)=
= -19 3/4 + 3 1/6 - ( 17/4 - 15/8)=
= - 19 9/12 + 3 2/12 - (34-15)/8 =
=-199/12 - 19/8 = - (398+57)/24 =
= - 455/24= -18 23/24
по действиям:
1) - 10- 9 3/4 = -19 3/4
2) 4 1/4 - 1 7/8 = 17/4 - 15/8 = (34-15)/8 = 19/8=2 3/8
3) -19 3/4 + 3 1/6 = -19 9/12 + 3 2/12 = -16 7/12
4) -16 7/12 - 2 3/8 = -16 14/24 - 2 9/24 = -18 23/24