Answer:
expand the numbers inside the root,
solve and bring out what can be taken out as a whole number,
then narrow everything down to one number,
which would then be ur answer
85. 2√48y^5 - 3y √12y³
=> 2√2 x 2 x 2 x 2 x 3 x y x y x y x y x y - 3y√2 x 2 x 3 x y x y x y
=> 2 x 2 x 2 x y x y√3y - 3y x 2y√ 3y
=>8y²√3y - 6y²√3y
=>2y²√3y