Question 672634
Given
(1) sqrt(-200)/(sqrt(-18)*sqrt(50)), (If it's other than this you can still solve it using two properties.) 
To solve we use two powerful properties of radicals.
(2) sqrt(a)*sqrt(b) = sqrt(a*b) and
(3) sqrt(a)/sqrt(b) = sqrt(a/b)
Using (2) on the denominator of (1) we get
(4) sqrt(-18)*sqrt(50) = sqrt(-900)
Now apply (3) to the numerator of (1) and the new denominator given by (4) to get
(5) sqrt(-200)/sqrt(-900) = sqrt(-200/-900) or
(6) sqrt(2/9)
Now apply the reverse of (3) to (6) to get
(7) sqrt(2/9) = sqrt(2)/sqrt(9) or
the final answer is
(8) sqrt(2)/3