Answer :
Rewrite √180 as √(6^2*5), pull terms out from under the radical to get 6√5
Rewrite √125 as √(5^2*5), pull terms out from under the radical to get 5√5
Now you have:
6√5 - 5√5 + √5 = 2√5 ( 2 the square root of 5.)
Rewrite √180 as √(6^2*5), pull terms out from under the radical to get 6√5
Rewrite √125 as √(5^2*5), pull terms out from under the radical to get 5√5
Now you have:
6√5 - 5√5 + √5 = 2√5 ( 2 the square root of 5.)