Answer :
Okay Aaron, he walks 1 mile in 20 minutes. Since we know that, we multiply 1/20 by 3 as the our numerator of 1 represents the mile and the denominator represents the time, he would travel a distance of 3 miles in 60 minutes.
[tex]4\ miles\ in\ 80\ minutes\\\\
x\ miles\ in\ 30\ minutes\\\\
proportion:\\
4-80\\x-30\\\\
cross\ multiplication\\\\
4*30=80x\\\\
120=80x\ \ \ \ | divide\ by\ 80\\\\ x=1.5\\\\
He\ walked \ 1.5\ miles.
[/tex]