Simplify 3 square root of 20 / square root of 5

-7√5

rewrite 20 as 2^2·5

factor 4 out of 20. negative ∛4 (5) - √5

rewrite 4 and 2^2 negative ∛2^2·5-√5

pull terms out from under the radical

-3 (2√5) √5

multiply 2 by - 3

-6√5-√5

subtract √5 from - 6√5

-7√5

the answer is - 7√5