Answer:
17 km
Step-by-step explanation:
The speed is 34 km/h.
He walks 34 km in 1 hour.
1 hour = 60 minutes.
He walks 34 km in 60 minutes.
30 minutes is half of 60 minutes, so in 30 minutes, he walks half the distance he walks in 60 minutes.
34 km / 2 = 17 km
In 30 minutes he walks 17 km