Answer:
Hardy Weinberg equilibrium states that in a population the amount of genetic variation remains constant from one generation to another generation in the absence of evolutionary disturbances. 
They Hardy-Weinberg equation is:
p² +2pq + q² = 1
p       =  dominant alleles frequency (A)
q       =  recessive alleles frequency (a)
p²     =  dominant homozygous genotype frequency (AA)
q²     =  recessive homozygous genotype frequency (aa)
2pq  =  heterozygous genotype frequency (Aa)
p² and 2pq =  dominant phenotype frequency (A)
q²     =  recessive phenotype frequency (a)
Note: A or a is for example in which A represent the dominant allele while a represent the recessive allele.