Exactly where is your difficulty?
. . You don't know the Quotient Rule?
. . You don't understand increasing/decreasing?
. . You can't handle inqualities?
Quotient Rule: .Find all open intervals on which the function is decreasing
The function is decreasing where
. . So we have: .
Since the denominator is always positive, we have: .
Therefore, is decreasing on the interval: .