Let x be the length of the road cleared before lunch.
The length cleared after lunch is x + 14 km.
We are given that x = (5/7)(x + 14).
7x = 5(x + 14)
7x = 5x + 70
2x = 70
x = 35 km (cleared before lunch).
Length cleared after lunch = 35 + 14 = 49 km.
Total length cleared = 35 + 49 = 84 km.