Answer:
400 meters
Step-by-step explanation:
We know that Barbara can walk 3,200 meters in 24 minutes . And are being asked to see how far she can walk in 3 minutes.
Create the unit rate. Since Barbara can walk 3,200 in 24 minutes and we're trying to figure out how many meters she walks in 3 mintues, make the meters "M"

Let's do something that can make 24 mintues go to 3 minutes, this would be dividing 24 by 8, do the same with the numerator :


Therefore Barbara can walk 400 meters in 3 minutes,