`a) (3x - 5)(7 - 5x) - (5x + 2) (2 – 3x) = 4`
`=>21x - 15x^2 – 35 + 25x - (10x – 15x^2 + 4 - 6x) - 4 =0`
`=>21x - 15x^2 - 35 + 25x - 10x + 15x^2 - 4 + 6x - 4= 0 `
`=>21x + 25x -10x + 6x = 4 +35+4 `
`=>32x = 43`
`=>x=43/42`
`b) 6x^2 - (2x + 5) (3x - 2) = 7 `
`=> 6x^2 – (6x^2 - 4x + 15x - 10) = 7 `
`=> 6x^2 - 6x^2 + 4x - 15x + 10 = 7 `
`=> 4x - 15x = 7 - 10 `
`=> -11x = -3 `
`=> x= 3/11`