Answer
$\dfrac{7}{15x^2}$
Restriction: $x \ne 0$; $y \ne 0$
Work Step by Step
To multiply two rational expressions, we multiply the numerical coefficients first:
$\dfrac{28x^2y}{60x^4y}$
Divide numerator and denominator by $4$ to simplify:
$\dfrac{7x^2y}{15x^4y}$
To divide exponents having the same bases, we subtract the exponents and keep the base as-is:
$\dfrac{7(x^{2 - 4})(y^{1 - 1})}{15}$
Subtract the exponents:
$\dfrac{7(x^{-2})(y^{0})}{15}$
We don't want negative exponents in our answer, so we change them into positive exponents and take their reciprocal. Also, replace $y^0$ with $1$:
$\dfrac{7}{15x^2}$
To see what restrictions for the variables we have, we need to see which values for the variables will make the denominator equal to $0$, which will cause the fraction to become undefined:
Restriction: $x \ne 0$; $y \ne 0$
