Respuesta :

WaleMaths
Speed = distance/time

T = 1/F

F = 1/T

Therfore: Speed = distance × frequency..

Where distance = wavelength..

Speed=340m/s

Wavelength = 20

340 = 20/T (where T=period)

T = 20/340

T = 1/17 secs.....

Hope this helped..?