Answer:

Explanation:
Given:
After lunch the friends walked 6 3/4 miles before arriving at the end of the trail.
The trail is 14 1/8 miles long.
Question asked:
How long did the friends walk before lunch ?
Solution:
Let the friends walk before lunch in miles = 

As total length of trail is given 
 , we can conclude:
Total length of trail = The friends walk before lunch in miles + The friends walk after lunch in miles

Subtracting both side by 

 

Taking LCM of 4 and 8 ,we get 8

Therefore, the friends walk before lunch is 
.