Bài `1:`
`a, 7/3 : 14/15 - 9/4`
`= 5/2 - 9/4`
`= (10 - 9)/4`
`= 1/4`
`b, 15 3/7 - (8/9 + 7 3/7)`
`= 15 3/7 - 8/9 - 7 3/7`
`= 8 - 8/9`
`= (72 - 8)/9`
`= 64/9`
`c, |-5/12| + ((-2)/3)^2. (20% - 1,2)`
`= 5/12 + 4/9. (1/5 - 1/2)`
`= 5/12 + 4/9. (-3)/10`
`= 5/12 - 2/15`
`= (25 - 8)/60`
`= 17/60`
`d, 5/9. 7/13 - 30/23 + 6/9. 5/13 + 7/23`
`= 5/9. 7/13 - 30/23 + 5/9. 6/13 + 7/23`
`= 5/9. (7/13 + 6/13) - 30/23 + 7/23`
`= 5/9 - 1`
`= -4/9`
Bài `2:`
`a, 3/4x - 1/3 = (-5)/6`
`⇒ 3/4x = (-5)/6 + 2/6`
`⇒ 3/4x = (-1)/2`
`⇒ x = (-2)/3`
`b, |-4/27| - 1 1/3x = (-2)/9`
`⇒ 4/27 - 4/3x = (-2)/9`
`⇒ 4/3x = 4/27 + 6/27`
`⇒ 4/3x = 10/27`
`⇒ x = 5/18`
`c, (1/4 - x)^2 - 125% = 1 13/16`
`⇒ (1/4 - x)^2 - 5/4 = 29/16`
`⇒ (1/4 - x)^2 = 49/16`
`TH1: 1/4 - x = 7/4`
`⇒ x = 1/4 - 7/4`
`⇒ x = -3/2`
`TH2: 1/4 - x = (-7)/4`
`⇒ x = 1/4 + 7/4`
`⇒ x = 2`
Vậy `x = -3/2` hoặc `x = 2`
