Divide and simplify:

$\displaystyle \frac{{{x}^{{2}}-{16}}}{{{x}^{{2}}-{1}{x}-{12}}}\div\frac{{{7}{x}}}{{{x}+{3}}}$

Enter the numerator and denominator separately in the boxes below. If the denominator is 1, enter the number 1. Do not leave either box blank. Answer: