Final answer:
The total amount of time Edwin spent driving from city X to city Z is 7 hours.
Step-by-step explanation:
To find the total amount of time Edwin spent driving from city X to city Z, we need to calculate the time taken for each leg of the journey and then add them up.
Given that Edwin drove 261 miles from city X to city Y in 4.5 hours at the same average speed, we can calculate the speed as follows: speed = distance / time = 261 miles / 4.5 hours = 58 miles/hour.
For the second leg of the journey, Edwin drove 145 miles. To find the time taken, we divide the distance by the speed: time = distance / speed = 145 miles / 58 miles/hour = 2.5 hours.
Adding the time taken for both legs of the journey, the total amount of time Edwin spent driving from city X to city Z is 4.5 hours + 2.5 hours = 7 hours.