Câu 1:
` a) ` ` (1276 - 1204) : 2006 - 16 `
` = 72 : 2006 - 16 `
` = 36/1003 - 16 `
` = -16012/1003 `
` b) ` ` 194.12 + 6.437.2 + 3.369.4 `
` = 12 .194 + 12 . 437 + 12 . 369 `
` = 12.(194 + 437 + 369) `
` = 12.1000 `
` = 12000 `
` c) 720: [41 - (3.5 + 6)] - 19 `
` = 720 : [ 41 - (15 + 6)] -19 `
` = 720 : (41 - 21 ) - 19 `
` = 720 : 20 - 19 `
` = 36 - 19 `
` = 17 `
Câu 2:
` (x-280) : 35=55:5 `
` <=> (x - 280) : 35 = 11 `
` <=> x - 280 = 11 . 35 `
` <=> x - 280 = 365 `
` <=> x = 365 + 280 `
` <=> x = 645 `
