Условие:

472
4720
543
54 + 30
7620
76 + 20
68 + 8 + 2
45 + 6 + 4

472 = (40 + 7) − 2 = 40 + (72) = 40 + 5 = 45
4720 = (40 + 7) − 20 = 7 + (4020) = 7 + 20 = 27
543 = (50 + 4) − 3 = 50 + (43) = 50 + 1 = 51
54 + 30 = (50 + 4) + 30 = (50 + 30) + 4 = 80 + 4 = 84
7620 = (70 + 6) − 20 = 6 + (7020) = 6 + 50 = 56
76 + 20 = (70 + 6) + 20 = (70 + 20) + 6 = 90 + 6 = 96
68 + 8 + 2 = (68 + 2) + 8 = 70 + 8 = 78
45 + 6 + 4 = 45 + (6 + 4) = 45 + 10 = 55