Nice.
Since we know that the distance to the store is the same forwards and backwards, we would make the distance the same.
Home => 6mph => store => 4mph => Home
Since one way is faster than the other we need to find the average between the both. As the average (5mph) would reveal the real length. As it would show the same distance for both sides.
12/5 is = 2.4
It's 2.4 miles backward and forwards.
