You have a population in hardy-weinberg equilibrium for the m and n alleles. these alleles are codominant. the allele frequency of m is 0.4. what is the frequency of heterozygotes in the population

48%

Because the population is in hardy-weinberg equilibrium, that means the sum of m and n alleles frequency would be 1
If m is 0.4, then n would be:
m+n=1
0.4+n=1
n=0.6

The frequency of organism with heterozygote genotype would be:
2 * m* n= 2 * 0.4 *0.6=0.48=48%