Perform the Indicated Operation Involving Rational Expressions $\frac { 9 a ^ { 5 } b ^ { 5 } } { 10 a ^ { 4 } c b ^ { 4 } } \div \frac { 72 c a ^ { 4 } b ^ { 5 } } { 70 a ^ { 6 } }$

Short Answer

Perform the indicated operation involving rational expressions. Express final answer in simplest form. $\frac { 9 a ^ { 5 } b ^ { 5 } } { 10 a ^ { 4 } c b ^ { 4 } } \div \frac { 72 c a ^ { 4 } b ^ { 5 } } { 70 a ^ { 6 } }$