A biologist is studying the appearance of three genotypes, denoted by A, B and C, in certain insects. For each of the three genotypes, the probability is 0.05 that an insect has only this genotype, and no others. For any two of the genotypes, the probability is 0.1 that an insect has exactly these genotypes, but not the other. The probability of an insect having all these three genotypes, given that it has A and B, is 0.75. Find the probability that an insect has none of the genotypes, given that it does not have genotype A.