About 21c because it also depends on the weather outside
The frequency of a wave is the number of complete oscillations passing a given point per second.
In this case, assuming the duck is stationary, we have 4 complete waves passing the duck in one second: therefore, the frequency of the wave is
Answer:
Average accelation = -4V
Explanation:

V=0 m/s (because the frog stopped)
V0 = V (average velocity)
t= 0,25 s
So;

A positive or direct relationship is one in which the two variables (we will generally call them x and y) move together, that is, they either increase or decrease together. In a negative or indirect relationship, the two variables move in opposite directions, that is, as one increases, the other descremases