Relate Wavelength Frequency Wave Speed Practice Test

An electromagnetic wave travels in vacuum at $c = 3.0\times 10^8\ \text{m/s}$. If its frequency increases while it remains in vacuum, what happens to its wavelength $\lambda$?

A water wave travels at a constant speed. If the frequency increases from $0.40\ \text{Hz}$ to $0.80\ \text{Hz}$ while the wave speed stays the same, what happens to the wavelength $\lambda$?