a) `-2/(7x) - 3 1/-5 = 3/5`
`2/(7x) = 3/5 + 3 (-1)/5`
`2/(7x) = 19/5`
`7x = 2 : 19/5`
`7x = 10/19`
`x = 10/133`
Vậy `x = 10/133`.
c) `-(3 - x) . 7 1/2 - 4/6 . 3 1/2 = -3`
`-(3 - x) . 7 1/2 - 7/3 = -3`
`-(3 - x) . 15/2 = -2/3`
`x - 3 = -4/45`
`x = 3 - 4/45`
`x = 131/45`
Vậy `x = 131/45`.
b) `-x . 4 7/2 - 3 1/-5 = -7/5`
`-15/2x + 16/5 = -7/5`
`-15/2x = -7/5 - 16/5`
`15/2x = -23/5`
`x = -23/5 : (-15/2)`
`x = 46/75`
Vậy `x = 46/75`.
d) `7 1/-2 . 3 (-1)/7 - (-3)/x = 1/-2`
`165/7 + 3/x = -1/2`
`3/x = -1/2 - 165/7`
`3/x = -337/14`
`x = 3 : (-337)/14`
`x = -42/337`
Vậy `x = -42/337`