`\text{d) 5x² (x - 1) - 15x (x - 1)}`
`\text{= (5x² - 15x) (x - 1)}`
`\text{= 5x (x - 3) (x - 1)}`
`\text{e) 3x (x - 2y) + 6y (2y - x)}`
`\text{= 3x (x - 2y) - 6y (x - 2y)}`
`\text{= (3x - 6y) (x - 2y)}`
`\text{= 3 (x - 2y) (x - 2y)}`
`\text{= 3 (x - 2y)²}`