23/4 miles is as much as 5 3/4 miles. We can also write it as a decimal, because 5 3/4 = 5,75 miles.
If Ammar hikes 5,75 miles in 1 1/4 hour, then we need to find out what distance does he hike in 1/4 hour (15 minutes). To do that we can just divide 5,75 by 5 (because dividing 1 1/4 by 5 will give us 1/4 we're looking for).
5,75 / 5 = 1,15
It means that in one hour Ammar hikes 5,75 - 1,15 = 4,6 miles.
