I have trouble with these 2 problems, can anyone assist me to answer them?

18) What is the speed of a periodic wave disturbance that has a frequency of 3.50 Hz and a wavelength of 0.700 m?

21) A periodic longitudinal wave that has a frequency of 20.0 Hz travels along a coil spring. If the distance between successive compressions is 0.600 m, what is the speed of the wave?

1 answer

18) Multiply wavelength by frequency.

21) 0.600 is in this case the wavelength. Once again, multiply ot by the frequency to get the wave speed.