`a) x + 2/7 = 3/14`
`x = 3/14 - 2/7 `
`x = 3/14 - 4/14`
`x = -1/14`
`Vậy x = -1/14`
`c) -3/11 - x = -5/22`
`x = -3/11 - -5/22`
`x = -6/22 + 5/22`
`x = -1/22`
`Vậy x = -1/22`
`b) x - 4/15 = 3/10`
`x = 3/10 + 4/15`
`x = 9/30 + 8/30`
`x = 17/30`
`Vậy x = 17/30`
`d) 7/20 - (2/5 + x) = 1/6`
`2/5 + x = 7/20 - 1/6`
`2/5 + x = 42/120 - 20/120`
`2/5 + x = 22/120`
`2/5 + x = 11/60`
`x = 11/60 - 2/5 `
`x = 11/60 - 24/60`
`x = -13/60`
`Vậy x = -13/60`