(2 1/4x³y)(2/3xy²)²

\frac{21}{4x {}^{3} y } \times \frac{4}{9x {}^{2} y {}^{4} } = \frac{3}{x {}^{3} y} \times \frac{1}{3x {}^{2}y {}^{4} } = \frac{1}{x {}^{5} y {}^{5} }