2 Află valoarea necunoscutei: a) (a x 2-40): 23 = 12 b) a : 2 + (123 x 3 - 53 × 4) = 257 c) aa+a-ax0 = 56 d) 2 x 111-5-[5 x 4+ (7+4): a] = 76 e) 9x [3+4x x (15+ 6xa): 18] = 81 f) [(a: 3-1): 6+ 489] : 25 + 2 = 26 g) (a:5-4):3-260 : 2 = 1 X = 10 h) 800: [425 - 13 x (484) - (89 + ax 4)] = i) [(625 : a + 65 x 7): 5]: 3-14 = 18 j) ax 4+ (6x7-5×6-72:8) × 76 = 332 k) (651 - 72x4-306: 2): ax 9 = 45 1) 1000 - a x [100: (7 x 12-74) - 5] = 500​