Ammar hikes 2 3/4 miles of nature trail in 1hr and 15 min how many miles of trail does ammar hike per hour?

D=distance; r=rate; and t=time.  The applicable formula is d=rt.  In this problem we know d and t and need only solve d=rt for r, the rate (speed):

d/t = r

2 3/4 becomes 11/4; 1 hr and 15 min becomes 1.25 hours.  The speed is thus r
         (11 mile)/4
r = = (11/4)(5/4) mph = (55/16) mph
         1.25 hour

If you wished, you could re-write this as 4 7/16 mph.