=3*3√7-[4√(1/5)+6√(1/7)+9√5/5]
=9√7-(4√5/5+6√7/7+9√5/5)
=9√7-(13√5/5+6√7/7)
=9√7-13√5/5-6√7/7
=(57/7)√7-(13/5)√5