Answer:
[tex] \purple { \bold{ \frac{ (x - 3)}{3x - 18} }}[/tex]
Step-by-step explanation:
[tex] \frac{x + 3}{ {x}^{2} + 7x + 12 } . \frac{ {x}^{2} + x - 12}{3x - 18} \\ \\ = \frac{x + 3}{ {x}^{2} + 4x + 3x + 12 } . \frac{ {x}^{2} + 4x - 3x - 12}{3(x - 6)} \\ \\ = \frac{x + 3}{ {x}(x + 4) + 3(x + 4) } . \frac{ {x}(x + 4) - 3(x + 4)}{3(x - 6)} \\ \\ = \frac{ \cancel{(x + 3)}}{ (x + 4) \cancel{(x + 3)} } . \frac{ (x + 4) (x - 3)}{3(x - 6)} \\ \\ = \frac{1}{ \cancel{ (x + 4)} } . \frac{ \cancel{ (x + 4)} (x - 3)}{3(x - 6)} \\ \\ \red{ \bold{= \frac{ (x - 3)}{3x - 18} }}\\ \\ [/tex]
