Question 57474
I think your problem is in this form
{{{9*sqrt(6)-9*sqrt(2)}}}
{{{sqrt(81)*sqrt(6)-sqrt(81)*sqrt(2)}}}
{{{sqrt(486)-sqrt(162)}}}
Find the greatest common number that can be divided by both answers: 54
{{{sqrt(9)*sqrt(54)-sqrt(3)*sqrt(54)}}}
{{{sqrt(54)*(sqrt(9)-sqrt(3))}}}
caluculator answer {{{9.3175}}}

You could just have skipped all the steps and used a calculator to find the answer using your original form