*Lời giải :
Bài 1
`a) 5 3/7 - (4 3/7 + 1)`
`= 5 3/7 - 4 3/7 - 1`
`= (5 3/7 - 4 3/7) - 1`
`= 1 - 1`
`= 0`
`b) (-5)/7 . 2/11 - 5/11 . 9/7 + 2 5/7`
`= 2/7 . (-5)/11 - 5/11 . 9/7 + 19/7`
`= (-5)/11 . (2/7 + 9/7) + 19/7`
`= (-5)/11 . 11/7 + 19/7`
`= (-5)/7 + 19/7`
`= 2`
Bài 2
`a) 4/9 + 7/3 : x = 1/5`
`-> 7/3 : x = 1/5 - 4/9`
`-> 7/3 : x = (-11)/45`
`-> x = 7/3 : (-11)/45`
`-> x = (-105)/11`
Vậy `x = (-105)/11`
`b) 60% x + 2/3x = -76`
`-> (60% + 2/3)x = -76`
`-> 19/15x = -76`
`-> x = -76 : 19/15`
`-> x = -60`
Vậy `x= -60`