Question 54397
Factor the top and bottom and cancel everything that matches between the top and the bottom (otherwise known as the numerator and denominator).
Special Factoring Pattern:{{{highlight(a^2-b^2=(a+b)(a-b))}}}
{{{4r^2-25s^2}}}
{{{(2r)^2-(5s)^2=(2r+5s)(2r-5s)}}}
{{{2r^2+3rs-20s^2=(2r-5s)(r+4s)}}}  
so the expression can be written as:
{{{(2r+5s)*(2r-5s)/((2r-5s)*(r+4s))}}}
{{{(2r+5s)*cross(2r-5s)/(cross(2r-5s)*(r+4s))}}}
{{{highlight((2r+5s)/(r+4s))}}}
Happy Calculating!!!