32 + 4 + 4 + 4;
27 − 9 − 9 − 9;
18 + 9 + 9;
14 − 7 − 7.
32 + 4 + 4 + 4 = 32 + (4 + 4 + 4) = 32 + 12 = (30 + 10) + (2 + 2) = 40 + 4 = 44
27 − 9 − 9 − 9 = 27 − (9 + 9 + 9) = 27 − 27 = 0
18 + 9 + 9 = 18 + (9 + 9) = 18 + 18 = (10 + 10) + (8 + 8) = 20 + 16 = 36
14 − 7 − 7 = 14 − (7 + 7) = 14 − 14 = 0