Answer:
It takes 30 minutes to get back
Explanation:
Jeffery biked to the store at 12 miles per hour. This is the speed at which he biked on his way to the store. He covered this distance to the store in 20 minutes.
Converting 20 minutes to hours, we divide by 60.
20 minutes =20/60 hours
Distance which Jeffrey covers on his way to the store at a speed of 12 miles/ hour and time of 20/60 hours is
Speed = distance / time
Distance = speed × time = 12× 20/60
= 4 miles.
The distance remains the same on his way back even though his speed reduced to 8 miles/ hour
Time taken to get back = distance/ speed
= 4 /8 = 0.5 hours
Converting to minutes
0.5 × 60 = 30minutes