Условие:

7 + 8;
17 + 8;
87 + 8;
6 + 9;
36 + 9;
56 + 9;
128;
628;
928;
146;
746;
946.

7 + 8 = 15;
17 + 8 = 10 + (7 + 8) = 10 + 15 = 25;
87 + 8 = 80 + (7 + 8) = 80 + 15 = 95;
6 + 9 = 15;
36 + 9 = 30 + (6 + 9) = 30 + 15 = 45;
56 + 9 = 50 + (6 + 9) = 50 + 15 = 65;
128 = 128 = 4;
628 = 50 + (128) = 50 + 4 = 54;
928 = 80 + (128) = 80 + 4 = 84;
146 = 146 = 8;
746 = 60 + (146) = 60 + 8 = 68;
946 = 80 + 8 = 88.