Question 62585
When you distribute the {{{5*sqrt(3)}}}, multiply the things inside the radicals by the things inside of the radicals and the things not under radicals by the things not under radicals.
{{{5*sqrt(3)(sqrt(5)-8)}}}  
{{{5*sqrt(3*5)+5(-8)sqrt(5)}}}
{{{5*sqrt(15)-40*sqrt(5)}}}
Happy Calculating and Happy Thanksgiving!!!