Answer:
The answer is : 20 seconds
Step-by-step explanation:
First, we are told that it takes the person 8 seconds to travel 56 feet, hence, we will find the time it takes to travel one foot.
56 feet = 8 seconds
∴ 1 foot = 8/56 seconds
Next, we are told that the length of the sidewalk is 140 feet, therefore walking from one end of the sidewalk to the other is the the same as walking 140 feet, and this is calculated thus:
1 foot = 8/56 seconds (calculated above)
∴ 140 feet = 8/56 × 140 = 20 seconds
