Add or Subtract by First Simplifying Each Radical and Then $x \sqrt { 6 x } + 5 \sqrt { 216 x ^ { 3 } } - 3 x \sqrt { 216 x }$

Add or subtract by first simplifying each radical and then combining any like radicals. Assume that all variables represent positive numbers.
- $x \sqrt { 6 x } + 5 \sqrt { 216 x ^ { 3 } } - 3 x \sqrt { 216 x }$

A) $2 x \sqrt { 6 x }$
B) $13 x \sqrt { 235 x }$
C) $13 x \sqrt { 6 x }$
D) $2 x \sqrt { 216 x }$