`a)`
`x+(-3/7)=4/7`
`=>x=4/7 -(-3/7)`
`=>x=4/7 + 3/7`
`=>x=7/7`
`=>x=1`
`b)`
`3/2 . x =-2/3`
`=>x=-2/3 : 3/2`
`=>x= -2/3 . 2/3`
`=>x= -4/9`
`c)`
`-5 4/7 : x=13`
`=> -31/7 : x= 13`
`=> x= -31/7 : 13`
`=> x= -13/7 . 1/13`
`=>x=-1/7`
`d)`
`1/2 x - 75% = 1/4`
`=>1/2 x - 3/4 = 1/4`
`=> 1/2 x = 1/4 + 3/4`
`=> 1/2 x = 1`
`=>x= 1 : 1/2`
`=>x=1 . 2/1`
`=>x=2/1`
`=>x=2`