Answer:
156m/s
Step-by-step explanation:
You can easily solve for this using the formula of the speed of a wave:

Where:
v = velocity/speed
f = frequency
λ = wavelength
In our problem we were given the following:
f=125Hz
λ = 1.25m
So we plug that into our formula:

If we round to the nearest whole number, the answer would be 156 m/s.