Question 691060
simplify {{{5sqrt(27) + 7sqrt(3)}}} 
Factor inside the 1st radical to reveal a perfect square
{{{5sqrt(9*3) + 7sqrt(3)}}} 
Extract the square root of 9
{{{5*3sqrt(3) + 7sqrt(3)}}} = {{{15sqrt(3) + 7sqrt(3)}}} 
Now we have like terms, just add them
{{{22sqrt(3)}}}