300 : 60 - 30 : (10 + 5) - 30
= 50 - 30 : 15 - 30
= 50 - 2 - 30
= 48 - 30
= 18.
2011 + 5 . [300 - 10 . (17 - 7)]
= 2011 + 5 . [300 - 10 . 10]
= 2011 + 5 . [300 - 100]
= 2011 + 5 . 200
= 2011 + 1000
= 3011.
29 - [16 + 3 . (51 - 49)]
= 29 - [16 + 3 . 2]
= 29 - [16 + 6]
= 29 - 22
= 7.
2010 - 2000 : [486 - 2 . (49 - 6)]
= 2010 - 2000 : [486 - 2 . 43]
= 2010 - 2000 : [486 - 86]
= 2010 - 2000 : 400
= 2010 - 500
= 1510.
cái câu 300 :60 - 30 ; ( 10 + 5 ) - 30 Nguyễn Thanh vân sai rồi tề, đáng lẽ 300 : 60 = 5 chớ