[tex](2 \frac{2}{5} \times 6 \frac{1}{4} ) {}^{4} = ( \frac{12}{5} \times \frac{25}{4} ) {}^{4} = ( \frac{3}{5} \times 25) {}^{4 } = (3 \times 5) {}^{4} = 15 {}^{4} [/tex]
