(51 – X) = 21 C) 690

Câu 3: Tìm x biết: (10p)a) (x – 51) . 23 = 0 b) 21. (51 – x) = 21 c) 690 : x = 15d) 30 – 2x = 6 e) 321 – (123 + x) = 111 g) (x + 15) – 32= 43h) 67 – 3x = 31 i) 18 + 3x = 24 k) (x – 36) : 18 = 12l) 0:x = 0