Question 54076
First you factor and then you cancel:
{{{4r^2-25s^2)/(2r^2+3rs-20s^2)}}}
The top is the difference of two squares {{{a^2-b^2=(a+b)(a-b)}}}
The denominator is {{{ax^2+bx+c}}}it has different methods of factoring, let me know what your teacher is using and I'll show you the steps.
{{{(4r^2-25s^2)/(2r^2+3rs-20s^2)=((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!!!