Answer:
(a).
[tex] \frac{2}{5a} = \frac{4}{a - 1} \\ \\ 20a = 2a - 2 \\ 18a =- 2 \\ a = - \frac{1}{9} [/tex]
(b).
[tex] \frac{7}{2d - 5} = \frac{9}{3d + 4} \\ \\ 7(3d + 4) = 9(2d - 5) \\ 21d + 28 = 18d - 45 \\ 3d = - 73 \\ d = - \frac{73}{3} [/tex]
(c).
[tex] \frac{3}{e + 1} + \frac{1}{2e + 1} = 0 \\ 3(2e + 1) = - (e + 1) \\ 6e + 3 = -(e + 1) \\ 7e = - 4 \\ e = - \frac{4}{7} [/tex]
(d).
[tex] \frac{5}{2f - 5} - \frac{4}{7f + 1} = 0 \\ \\ \frac{5}{2f - 5} = \frac{4}{7f + 1} \\ \\ 5(7f + 1) = 4(2f - 5) \\ 35f + 5 = 8f - 20 \\ 27f = - 25 \\ f = - \frac{25}{27} [/tex]
(d).
