Rationalizing the denominator of 305√3−3√5.
305√3−3√5×(5√3+3√5)(5√3+3√5)
=30(5√3+3√5)(5√3)2−(3√5)2
=30(5√3+3√5)75−45
=30(5√3+3√5)30
=5√3+3√5