each product. Simplify as much as possib \( 7 x y\left(3 x^{2} y^{3}\right) \)

To simplify \( 7 x y\left(3 x^{2} y^{3}\right) \), you simply multiply the coefficients and add the exponents for like bases. First, multiply the coefficients: \( 7 \cdot 3 = 21 \). Next, combine the terms \( x \) and \( x^{2} \) which gives \( x^{1 + 2} = x^{3} \), and for \( y \) and \( y^{3} \), it becomes \( y^{1 + 3} = y^{4} \). Putting it all together, the expression simplifies to \( 21 x^{3} y^{4} \).