Verified answer

[tex]1) \\ [/tex]

[tex] \frac{a - b}{2(b - a)} = \frac{a - b}{ - 2(a - b)} = - \frac{1}{2} = - 0.5 \\ [/tex]

[tex]2) \\ [/tex]

[tex] \frac{3x - 6y}{4y - 2x} = \frac{3(x - 2y)}{ - 2(x - 2y)} = \frac{ - 3}{2} = - 1.5 \\ [/tex]

[tex]3) \\ [/tex]

[tex] \frac{ {m}^{2} - 5mn }{15n - 3m} = \frac{m(m - 5n)}{ - 3(m - 5n)} = - \frac{m}{3} \\ [/tex]

[tex]4)[/tex]

[tex] \frac{ {7a}^{4} - {a}^{3} b }{b {}^{4} - 7ab {}^{3} } = \frac{ {a}^{3}(7a - b) }{ - {b}^{3}(7a - b) } = - \frac{ {a}^{3} }{ {b}^{3} } \\ [/tex]