Which do you need to calculate the speed of a wave?

To calculate the speed of a wave you need its frequency ( Hz) and wavelength
(m)

Once you have it slot in into this equation c = f *  λ
where c =speed of the wave
            f = frequency
             λ = wavelength

Hope this helps :).

Speed, v = fλ

where f = frequency in Hz, and λ = wavelength in m.

Hence to calculate the speed, you need to the know the value of the frequency and wavelength of the wave.