5 + 2 + 5 + 8 = (5 + 5) + (2 + 8) = 10 + 10 = 20
3 + 6 + 7 + 4 = (3 + 7) + (6 + 4) = 10 + 10 = 20
30 + 3 + 60 + 7 = (30 + 60) + (3 + 7) = 90 + 10 = 100
1 + 40 + 9 + 50 = (1 + 9) + (40 + 50) = 10 + 90 = 100
12 + 7 + 18 + 3 = (12 + 18) + (7 + 3) = 30 + 10 = 40
7 + 20 + 30 + 3 = (7 + 3) + (20 + 30) = 10 + 50 = 60
16 + 5 + 5 + 4 = (16 + 4) + (5 + 5) = 20 + 10 = 30
30 + 20 + 4 + 6 = (30 + 20) + (4 + 6) = 50 + 10 = 60
1 + 2 + 9 + 8 = (1 + 9) + (2 + 8) = 10 + 10 = 20