a) \(\frac{4x^2}{5y^2}.\frac{5y}{6x}.\frac{3y}{2x}=\frac{4x^2.5y.3y}{5y^2.6x.2x}=1\)
b)\(\frac{\left(x-2\right)\left(x+2\right)}{3\left(x+4\right)}.\frac{x+4}{2\left(x-2\right)}=\frac{x+2}{6}\)
c) \(\frac{\left(x-6\right)\left(x+6\right)}{2\left(x+5\right)}.\frac{-3}{x-6}=\frac{-3\left(x+6\right)}{2\left(x+5\right)}\)