a)
`x` - `1/3` = `2/7`
`x` = `2/7` + `1/3`
`x` = `7/21` + `6/21`
`x` = `13/21`
2)
`4/5` + `1/5` : `x` = `1/6`
`1/5` : `x` = `1/6` - `4/5`
`1/5` : `x` =`5/30` - `24/30`
`1/5` : `x` =`-19/30`
`x` = `1/5`: `-19/30`
`x` = `-6/19`
3)
`3/2` `x` -`1/2` ( `x`-1) = `5/2`
`3/2` `x` - `1/2` `x` - `1/2` . `1` = `5/2`
`3/2` `x` - `1/2` `x` -` 1/2` = `5/2`
`3/2` `x` - `1/2` `x` = `5/2` + `1/2`
`3/2` `x` - `1/2` `x` = `3`
`x` ( `3/2` - `1/2`) = 3
`x` . 2 = 3
`x` = 3: 2
`x` = 1,5
