Условие:

20 + 4 + 4 + 4
36666
40 + 5 + 5 + 5
70 + 3 + 3 + 3
80222
90777

20 + 4 + 4 + 4 = 20 + (4 + 4 + 4) = 20 + (8 + 2 + 2) = 20 + (10 + 2) = (20 + 10) + 2 = 30 + 2 = 32
 
36666 = 3066 = 30 − (6 + 6) = 3012 = 30102 = 202 = 18
 
40 + 5 + 5 + 5 = 40 + (5 + 5 + 5) = 40 + (10 + 5) = (40 + 10) + 5 = 50 + 5 = 55
 
70 + 3 + 3 + 3 = 70 + (3 + 3 + 3) = 70 + 9 = 79
 
80222 = 80 − (2 + 2 + 2) = 806 = (70 + 10) − 6 = 70 + (106) = 70 + 4 = 74
 
90777 = 90 − (7 + 7 + 7) = 90 − (14 + 7) = 90 − (14 + 6 + 1) = 90 − (20 + 1) = (9020) − 1 = 701 = 69