Gametes, which are sex cells, carry the alleles. Why must a gamete carry one allele (represented by a letter) from each gene? Meaning, why can’t a gamete carry an “hh” instead of an “hs” or an “Hh” instead of a “HS?

Suppose that sahil knows that 45 people with ages of 18 to 29 voted. without using a calculator, he quickly says then 135 people with ages of 30to 49 voted. is he correct? how might sohil have come up with his answer so quickly?