The answer is [tex] \frac{3d}{ c^{3}}[/tex]
The fraction is: [tex] \frac{27 c^{4} d^{5}}{9 c^{7} d^{4} } [/tex]
Let's rewrite it: [tex]\frac{27 c^{4} d^{5}}{9 c^{7} d^{4} }= \frac{27}{9}*\frac{c^{4}}{c^{7}}*\frac{d^{5}}{d^{4} }[/tex]
Now, let's use the rule [tex] \frac{ x^{a} }{ x^{b}} = x^{a-b} = \frac{1}{ x^{b-a} } [/tex]:
[tex]\frac{27}{9}*\frac{c^{4}}{c^{7}}*\frac{d^{5}}{d^{4} }=3* \frac{1}{c^{7-4}} * d^{5-4} =3* \frac{1}{ c^{3} } *d^{1}= \frac{3d}{ c^{3} } [/tex]