assuming that dot means multiply
remember
[tex](\frac{a}{b})(\frac{c}{d})=\frac{ac}{bd}[/tex]
so
remember that it is helpful to factor them to simplify
[tex](\frac{x-5}{3x+12})(\frac{2x+8}{2x-10})=[/tex]
[tex]\frac{(x-5)(2x+8)}{(3x+12)(2x-10)}=[/tex]
[tex]\frac{(x-5)(2)(x+4)}{(3)(x+4)(2)(x-5)}=[/tex]
[tex](\frac{(x-5)(2)(x+4)}{(x-5)(2)(x+4)})(\frac{1}{3})=[/tex]
[tex](1)(\frac{1}{3}=[/tex]
[tex]\frac{1}{3}[/tex]
