Instead of dividing 48 by 3, it appears that you subtracted 3 from 48. You may have confused division of coefficients with division with exponents. You then found the cube root of $\displaystyle{45}{x}{{y}}^{{4}}\usepackage{cmbright}\Huge\$ . Instead, rewrite using $\displaystyle\frac{{{\sqrt[{{3}}]{{a}}}}}{{{\sqrt[{{3}}]{{b}}}}}={\sqrt[{{3}}]{{\frac{{a}}{{b}}}}}\usepackage{cmbright}\Huge\$ . Identify common factors in the numerator and denominator and simplify. Identify perfect cubes and pull them out of the radical.