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