Answer:
2.4 km.
Let's see the 3 km as metres:
1 km = 1000 m
3 km = ?
1000 × 3 = 3000 m
How many metres is 1 minute:
25 minutes = 3000 m
1 minute = ?
3000 ÷ 25 = 120 m
How many metres is 20 minutes:
1 minute = 120 m
20 minutes = ?
120 × 20 = 2,400 m
Turn it to km:
1000 m = 1 km
2,400 m = ?
2,400 ÷ 1000 = 2.4 km.
The answer is 2.4 km.