For a gene that exists in two alleles, the Hardy-Weinberg equation states that $\left(p^2\right)+\left(2pq\right)+{\left(q\right)}^2=1$

$f\left(AA\right)=p^2$ (genotype frequency of homozygotes)

$f\left(Aa\right)=2pq$ (genotype frequency of heterozygotes)

$f\left(aa\right)=q^2$ (genotype frequency of homozygotes)

$f\left(AA\right)=p^2={\left(0.7\right)}^2=0.49$