Answer :
B). 2 Hours
Explanation if the older brother can run 6 MPH and it’s takes him a hour and twenty minutes you automatically can say it’s at least 6 miles then you have to see how many he can run in 20 minutes which is roughly 2 miles so that would mean he run for 8 miles if the younger brother can run 4 MPH then you just have to add that by 2 too see how long it will take to run 8
Explanation if the older brother can run 6 MPH and it’s takes him a hour and twenty minutes you automatically can say it’s at least 6 miles then you have to see how many he can run in 20 minutes which is roughly 2 miles so that would mean he run for 8 miles if the younger brother can run 4 MPH then you just have to add that by 2 too see how long it will take to run 8
The answer is 45 for this just plug in your variables to the equation