Hi there,waves are a kind of energy.Imagine a wave just like a car that is moving.It has speed, time, acceleration,frequensy, and also length.waves are like the diagram of sin(x).when we wanna find the speed of a moving thing, we just divide relocation by time.And we have some thing like that for a wave, we divide wavelength by its time, and also you have to know that, 1 divide by the waves time is equals frequency, it means: 1/T=f(Hz).So we had: Speed=Wavelength*1/TimeSo that we know from the point: Speed=Wavelength*frequencyIf there is any problem, you can ask again.GOODLUCK