Условие:

8 + 17
6 + 28
4 + 39
638
30 − (6 + 6)
40 − (7 + 7)
50 − (8 + 8)
60 − (9 + 9)
62 + 302
20 + 75 + 5
8360 + 7
7240 + 8

8 + 17 = 8 + (7 + 10) = (8 + 7) + 10 = 15 + 10 = 25
 
6 + 28 = (4 + 2) + 28 = 4 + (2 + 28) = 4 + 30 = 34
 
4 + 39 = (3 + 1) + 39 = 3 + (1 + 39) = 3 + 40 = 43
 
638 = 6335 = 605 = 55
 
30 − (6 + 6) = 3012 = 30102 = 202 = 18
 
40 − (7 + 7) = 4014 = 40104 = 304 = 26
 
50 − (8 + 8) = 5016 = 50106 = 406 = 34
 
60 − (9 + 9) = 6018 = 60108 = 508 = 42
 
62 + 302 = 2 + (60 + 30) − 2 = (22) + 90 = 0 + 90 = 90
 
20 + 75 + 5 = (20 + 70) + (5 + 5) = 90 + 10 = 100
 
8360 + 7 = 3 + (8060) + 7 = 20 + (3 + 7) = 20 + 10 = 30
 
7240 + 8 = 2 + (7040) + 8 = 30 + (2 + 8) = 30 + 10 = 40