Answer:
4 hours
Explanation:
John is hiking 9 miles. If it takes him an hour for every 3 miles, then you will do 9 ÷ 3.
9 ÷ 3 = 3
And it is stated that after every 4 miles, he takes a swim.
There will only be two swimming breaks since 4 can only go into 9 twice.
And two swim breaks will add up to an hour, adding an additional hour onto the 3 hours it takes for him to normally hike.
So, John hikes the 9 miles in 4 hours.