A. 2000 + 4000⨯ 2 = 10000(2000 + 4000)⨯ 2 = 12000B. 18000 – 4000...

Câu 1.a. 2000 + 4000⨯ 2 = 10000(2000 + 4000)⨯ 2 = 12000b. 18000 – 4000 : 2 = 16000(18000 – 4000) : 2 = 7000