Answer:
Total time for which they ride = ![\bold{7\ hours}](https://tex.z-dn.net/?f=%5Cbold%7B7%5C%20hours%7D)
Number of miles they ride each way = <em>24 mi</em>
Step-by-step explanation:
Average speed = 8 mi/hr
Let the Distance to Mill Park =
mi
Let the time taken =
hours
Formula:
![Distance = Speed \times Time](https://tex.z-dn.net/?f=Distance%20%3D%20Speed%20%5Ctimes%20Time)
..... (1)
Now, when average speed = 7 mi/hr
Time taken is 1 hour more, i.e. Time =
hours
Distance traveled is 4 mi more, i.e.
mi
Using the Formula:
![Distance = Speed \times Time](https://tex.z-dn.net/?f=Distance%20%3D%20Speed%20%5Ctimes%20Time)
![D+4=7\times (t+1)](https://tex.z-dn.net/?f=D%2B4%3D7%5Ctimes%20%28t%2B1%29)
From equation (1):
![8t+4=7t+7\\\Rightarrow t=3\ hours](https://tex.z-dn.net/?f=8t%2B4%3D7t%2B7%5C%5C%5CRightarrow%20t%3D3%5C%20hours)
From equation (1):
![D = 8 \times 3 = 24\ mi](https://tex.z-dn.net/?f=D%20%3D%208%20%5Ctimes%203%20%3D%2024%5C%20mi)
Total time for which they ride = ![t+t+1 = \bold{7\ hours}](https://tex.z-dn.net/?f=t%2Bt%2B1%20%3D%20%5Cbold%7B7%5C%20hours%7D)
Number of miles they ride each way = <em>24 mi</em>