Bài 1:
` a) ` ` 2x + 1/3 = 2/5 - (-1/3) `
` <=> 2x + 1/3 = 11/15 `
` <=> 2x = 2/5 `
` <=> x = 1/5 `
` b) ` ` 3/7 - x = 1/4 - (-3/5) `
` <=> 3/7 - x = 17/20 `
` <=> x = -59/140 `
Bài 2:
` a) ` ` 1/12 - (-1/6 - 1/4) `
` = 1/12 + 2/12 + 3/12 `
` = 1/2 `
` b) ` ` 1/2 - (-1/3) + 1/23 + 1/6 `
` = 3/6 + 2/6 + 1/6 + 1/23 `
` = 1 + 1/23 `
` = 24/23 `
` c) ` ` 2/3 - 4.(1/2 + 3/4) `
` = 2/3 - 2 - 3 `
` = 2/3 - 5 `
` = 2/3 - 15/3 `
` = -13/3 `