If the distance between the compression and rarefaction of a wave is 6 cm, then calculate its wavelength

If the distance between the compression and rarefaction of a wave is 6 cm, then calculate its wavelength.

Wavelength is the distance between two compressions or rarefactions. In other words, wavelength is a combined length of a compression and an adjacent rarefaction, i.e.
2 x 6 cm = 12 cm
Therefore, wavelength of the wave is 12 cm.