Question: Perform the indicated operations.

a) \(\frac{2x}{{{x}^{2}}-9}+\frac{x-1}{{{x}^{2}}+4x+3}\)

b) \(\frac{{{x}^{2}}-6x}{2{{x}^{2}}-5x-3}\,\,\,\div \,\,\,\frac{2x-12}{{{x}^{2}}+2x-15}\)