A diploid organism has two alleles for each gene. So, a population of 100 plants will have total 100 x 2 = 200 alleles.
The each of the white colored plants have two copies of CW alleles and each pink flowered plant have only one CW allele.
Frequency of CW allele in the population = total number of white flowered plants x 2 + total number of pink colored plants / total population size x 2.
Frequency of CW allele in the population= 22 x 2 + 38 / 100 x 2 = 82 /200 = 0.41