Question 256858
Your story doesn't make sense. Judge Judy is fond of saying if a story doesn't make sense it is probably not true. A more believable story is that you found the answer in the back of the book and don't want to or don't know how to solve the problem.
{{{3*sqrt(20)}}}={{{3*sqrt(4*5)}}}= {{{3*sqrt(4)}}}*{{{sqrt(5)}}}={{{3*2sqrt(5)}}}={{{6sqrt(5)}}}
So {{{2sqrt(5)}}}+{{{6sqrt(5)}}}={{{8sqrt(5)}}}