A sinusoidal wave moving to the left has a wavelength of 5.0 cm and a frequency of...?

A sinusoidal wave moving to the left has a wavelength of 5.0 cm and a frequency of 50 Hz. At t = 0 s, the wave has a crest at x = 0 cm. What is the earliest time after t = 0 s at which there is a crest at the position x = 3.6 cm?