Пошаговое объяснение:

1) (-3.8+2 1/3)*(-1 7/8) + 4 1/6 : (-1 2/3)=1,5

-3,8+2 1/3=-3 4/5+2 1/3=-19/5+7/3=

=(-19*3+7*5)/15=-36/15

-36/15*(-1 7/8) =36/15*15/8=4

4 1/6 : (-1 2/3)=25/6:(-5/3)=-25/6*3/5=-5/2=

=-2,5

4-2,5=1,5

2) (2.5-1 5/6): 1 4/9 - 3 5/9 *(-2 1/4)=8 6/13

2.5-1 5/6=2 1/2-1 5/6= 5/2-11/6=(5*3-11)/6=4/6=2/3

2/3:1 4/9=2/3*9/13=6/13

- 3 5/9 *(-2 1/4)=32/9*9/4=8

6/13+8=8 6/13

3) (-5/12 - 3/4) : 2 1/3 + 5 1/3 * 0.75=3,5

-5/12 - 3/4=-5/12 - 9/12=-14/12=-7/6

-7/6:2 1/3=-7/6*3/7=-1/2=-0,5

5 1/3 * 0.75=16/3*3/4=4

-0,5+4=3,5

4)(3/4 - 1 7/8) : 3/4 + 3 1/9 *3/7=-1/6

3/4 - 1 7/8=(6-15)/8=-9/8

-9/8:3/4=-9/8*4/3=-3/2

3 1/9 *3/7=28/9*3/7=4/3

-3/2+4/3=(-9+8)/6=-1/6