Question 55512
Multiply

{{{((2x^2-x-3)/(3x^2+7x+4))* ((3x^2-11x-20)/(4x^2-9))}}} 
Factor, Factor, Factor.  I'm using the arch or ac method.  If a polynomial is in {{{ax^2+bx+c}}} form.  Replace b with two numbers that multiply to give you a*c, but add together to give you b.  Then factor by grouping.
{{{((2x^2-3x+2x-3)/(3x^2+4x+3x+4))*((3x^2-15x+4x-20)/((2x+3)(2x-3)))}}}
{{{((x(2x-3)+1(2x-3))/(x(3x+4)+1(3x+4)))*((3x(x-5)+4(x-5))/((2x+3)(2x-3)))}}}
{{{(((x+1)(2x-3))/((x+1)(3x+4)))*(((3x+4)(x-5))/((2x+3)(2x-3)))}}}
Cancel the matching numerators and denominators:
{{{(cross((x+1))*cross((2x-3)))/(cross((x+1))*cross((3x+4)))*(cross((3x+4))*(x-5))/((2x+3)*cross((2x-3)))}}}
{{{highlight((x-5)/(2x+3))}}}
Happy Calculating!!!