Answer:
4/3
Explanation:
Since this is a fraction within a square root, you can take the square root of the top and bottom, sqrt25=5, sqrt16=4, so your answer is 5/4
To check, (5/4)^2=25/16
As a little "proof" that you can take the square root of a fraction this way, if you know this is true (x/y)^2=(x^2)/(y^2) then think about the square root of this as (x/y)^1/2=(x^1/2)/(y^1/2). (a number raised to the 1/2 is the same as square rooting it)