if my dad goes 15 miles to a gas station to get milk, and goes 2 miles per hour how long will it be for him to get back home?
30 miles round trip 30 m / 2 m/hr = 15 hr
The milk will be sour by the time he returns ...
Actually, 15 hours is for the whole trip, it will take him only 7.5 hours fo get back home ...
