39 + (45 - 12) = 39 + 33 = 72
40 + (37 + 11) = 40 + 48 = 88
37 + (49 + 6) = 37 + 55 = 92
27 + (90 - 42) = 27 + 48 = 75
42 : 7 * 3 = 6 * 3 = 18
54 : 6 * 9 = 9 * 9 = 81
64 : 8 * 4 = 8 * 4 = 32
63 : 9 * 6 = 7 * 6 = 42