Multiply and simplify:

$\displaystyle \frac{{{x}^{{2}}+{4}{x}-{21}}}{{{x}^{{2}}-{9}}}\cdot\frac{{{x}^{{2}}-{25}}}{{{x}^{{2}}+{12}{x}+{35}}}$

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: