`a, (x - 2)(5x - 1) - 5x(x - 3) = 5`
`⇒ 5x^2 - x - 10x + 2 - 5x^2 + 15x = 5`
`⇒ -x - 10x + 15x + 2 = 5`
`⇒ 4x = 3`
`⇒ x = 3/4`
`b, (4x + 1)(x - 3) - (x - 7)(4x - 1) = 15`
`⇒ 4x^2 - 12x + x - 3 - (4x^2 - x - 28x + 7) = 15`
`⇒ 4x^2 - 12x + x - 3 - 4x^2 + x + 28x - 7 = 15`
`⇒ -12x + x + x + 28x - 3 - 7 = 15`
`⇒ 18x -10 = 15`
`⇒ 18x = 25`
`⇒ x = 25/18`
