1.

1.8-2.2=

-0.14+0.17=

-2.18-1.54=

-7.8+5.6=

2.

-2/3 + 1/6 =

7/9 - 1/6=

-3/8 - 1/2=

3.

- (5.4) + (-2.8) + 4.6 - (+15.2) =

(1)

1.8-2.2 = - 0.4

-0.14+0.17 = 0.03

-2.18-1.54 = - 3.72

-7.8+5.6 = - 2.2

(2)

-2/3+1/6 = - 4/6+1/6 = - 3/6 = - 1/2 = - 0.5

7/9-1/6 = 14/18-3/18 = 11/18

-3/8-1/2 = - 3/8-4/8 = - 7/8

(3)

- (5.4) + (-2.8) + 4.6 - (+15.2) = - 5.4-2.8+4.6-15.2 = - 18.8