1)
(4+1.8) + 2.2 = 4 + 4 = 8
1.6 + (5 + 3.4) = 5 + 5 = 10
(2.41 + 13) + 4.59 = 13 + 7 = 20
2)
0.3 + (1.7 + 2.5) = 2 + 2.5 = 4.5
(3.8 + 6) + 4.2 = 8 + 6 = 14
12.25 + (8 + 3.75) = 16 + 8 = 24
3)
8.3 + (2.7 + 8) = 11 + 8 = 19
10.2 + (1.7 + 4.8) = 15 + 1.7 = 16.7
(46.3 + 18) + 4.7 = 51 + 18 = 69