1: (7 - 1) 3 122: ((7 - 1) 3) 123: (7 - 1) (3 12)4: (7 - 1) 12 35: ((7 - 1) 12) 36: (7 - 1) (12 3)7: 12 3 (7 - 1)8: (12 3) (7 - 1)9: 12 (3 (7 - 1))10: (12 (7 - 1)) 311: 12 (7 - 1) 312: 12 ((7 - 1) 3)