Answer:
[tex] \frac{x + 13}{8} = \frac{21}{x - 9} \\ {x}^{2} + 4x - 117 = 168 \\ {x}^{2} + 4x - 285 = 0 \\ (x - 15)(x + 19) = 0 \\ x = 15 \\ x = - 19[/tex]
