Don’t trust the person above me
Answer: The answer is in the first image.
Explanation: The explanation is in the second image.
The amount of time required to travel a certain distance is equal to quotient of distance and speed. We let x be the speed of Terry and Mark's will be x+2. The equation that would best represent the scenario is,
15/x = 21/(x+2)
The value of x is 5. Thus, Mark's speed is 7 mph.
The answer is 12 hours. It would take 12 hours.