(3+root5)/ (2root5+3) = a+b root5
LHS =(3+root5) / (2root5+3)
= (3+root5)×(2root5-3) / (2root5+3)×(2root5-3)
=6root5-9+10-3root5 / (2root5)^2 - (3)^2
=1+3root5 / 20-9
=1+3root5/11
=1/11 + 3root5/11
LHS = RHS
1/11 + 3root5/11 = a+b root5
hence,
a = 1/11 and b = 3/11