Verified answer

what you need to do is multiply by its conjugate on the numerator and denominator

√3/( 2-4√5)* (2+4√5)/ (2+4√5)

= √3* (2+4√5)/ (4- 16*5)

(a+b) (a-b)= a^2-b^2

= (2√3+4√15)/ -76

√(3)/(2-4√5)

√(3)/2(1-2√5)

(√3+2√15)/2(1-20)

-(√3+2√15)/38