$\frac{ {x}^{15}{y}^{30} }{ 64 } \times {\left( \frac{ {x}^{4}{y}^{30} }{ {4}^{2} } \right)}^{-1}$
Any expression raised to the power of $-1$ equals its reciprocal$\frac{ {x}^{15}{y}^{30} }{ 64 } \times \frac{ {4}^{2} }{ {x}^{4}{y}^{30} }$
Write the number in exponential form with the base of $4$$\frac{ {x}^{15}{y}^{30} }{ {4}^{3} } \times \frac{ {4}^{2} }{ {x}^{4}{y}^{30} }$
Cancel out the common factor ${y}^{30}$$\frac{ {x}^{15} }{ {4}^{3} } \times \frac{ {4}^{2} }{ {x}^{4} }$
Cancel out the common factor ${x}^{4}$$\frac{ {x}^{11} }{ {4}^{3} } \times {4}^{2}$
Cancel out the common factor ${4}^{2}$$\frac{ {x}^{11} }{ 4 }$