`a, (3 1/2 - 2.x) : 3 1/3 = 7 1/3`
`=> 3 1/2 - 2x = 7 1/3 . 3 1/3`
`=> 3 1/2 - 2x = 22/3 . 10/3`
`=> 3 1/2 - 2x = 220/3`
`=> 2x = 3 1/2 - 220/3`
`=> 2x = 7/2 - 220/3`
`=> 2x = -419/6`
`=> x = -419/6 : 2`
`=> x = -419/6 . 1/2`
`=> x = 419/12`
`b, 4/9 . x = 9/8 - 0,125`
`=> 4/9 . x = 9/8 - 125/1000`
`=> 4/9 . x = 9/8 - 1/8`
`=> 4/9 . x = 8/8`
`=> 4/9 . x = 1`
`=> x = 1 : 4/9`
`=> x = 1 . 9/4`
`=> x = 9/4`