The rate of the slower hiker is 1.1 mph and the rate of the faster hiker is 6.6 mph
Explanation
One hiker walks 5.5 mph faster than the other.
Suppose, the speed of the slower hiker is (x) mph.
So, the speed of the faster hiker will be:
(x+5.5)mph
Both hikers are walking toward each other and meet in 10 hours.
We know that, Distance = speed * time
So, the distance walked by the slower hiker in 10 hours = 10x miles and the distance walked by the faster hiker in 10 hours = 10(x + 5.5) miles.
Given that, they were 77 miles apart in the beginning. So the equation will be ...
10x + 10(x + 5.5) = 77
10x + 10x + 55 = 77
20x = 77 - 55 = 22
x = 22/20 = 1.1
Thus, the rate of the slower hiker is 1.1 mph and the rate of the faster hiker is (1.1 + 5.5) mph = 6.6 mph