Question 945507
Simple is a relative term.
What a math teacher would want you to do is rationalize.
Rationalize means convert that expression into an equivalent expression that does not have any irrational number (square root or the like) in the denominator.
To do that you use the "conjugate" of the  denominator,
a factor that multiplied times the denominator gives ypu a nice rational number.
Since {{{(10+sqrt(5))*(10-sqrt(5))=10^2-(sqrt(5))^2=100-5=95}}} ,
you multiply numerator and denominator times {{{(10-sqrt(5))}}} .
{{{(10-sqrt(5))/(10+sqrt(5))=(10-sqrt(5))*(10-sqrt(5))/((10
+sqrt(5))*(10-sqrt(5)))=(10-sqrt(5))^2/95=(100-2sqrt(5 )+5)/95}}}