Question 64789
{{{r^2-9tw+3rw-3rt}}}
Rearrange
{{{r^2+3rw-3rt-9tw}}}
Take a common factor from the first two terms and take a common factor from the third and fourth terms.
{{{r(r+3w)-3t(r+3w)}}}
Take a common factor of (r+3w) from each term to get
{{{(r+3w)(r-3t)}}}