we have the expression
[tex]\frac{3a^2+3a}{a^2-36}\cdot\frac{a^2-6a}{12a}[/tex]
Simplify
we have that
a^2-36=(a+6)(a-6)
3a^2+3a=3a(a+1)
a^2-6a=a(a-6)
substitute in the given expression
[tex]\frac{3a(a+1)}{(a+6)(a-6)}\cdot\frac{a(a-6)}{12a}[/tex]
Simplify
[tex]\frac{(a+1)}{(a+6)}\cdot\frac{a}{4}[/tex]
therefore
the answer is
[tex]\frac{(a^2+a)}{(4a+24)}[/tex]
