`a) 3/5 + (-4)/3 + (-3)/4`
`= 36/60 - 80/60 - 45/60`
` = -89/60`
`b) x - 2/7 = 7/21`
`=> x - 2/7 = 1/3`
`=> x = 1/3 + 2/7`
`=> x = 13/21`
Vậy `x=13/21`
`c) 11/12 - (2/5 + x) =2/3`
`=> 2/5 + x = 11/12 - 2/3`
`=> 2/5 + x = 1/4`
`=> x = 1/4 - 2/5`
`=> x = -3/20`
Vậy `x=-3/20`
`d) 3/7 - x = 1/4 - (-3/5)`
`=> 3/7- x = 17/20`
`=> x = 3/7 - 17/20`
`=>x = -59/140`
Vậy `x = -59/140`
`e) 3/35 - (3/5 + x) = 2/7`
`=> 3/5 + x = 3/35 - 2/7`
`=> 3/5 + x = -1/5`
`=> x = -1/5 - 3/5`
`=> x = -4/5`
Vậy `x=-4/5`
`f) 2/9 - (1/3 - x) = 5/6`
`=> 1/3 - x= 2/9 - 5/6`
`=> 1/3 - x = -11/18`
`=> x = 1/3+ 11/18`
`=> x = 17/18`
Vậy `x=17/18`
`g) 4 1/5 : (-2 4/5)`
` = 21/5 : (-14)/5`
` = 21/5 . (-5)/14`
` = -3/2`