The answer is -60.
Why is this so??
The information we have here is that Rafeal rode his bike downhill by 6 kilometers.
Every kilometer he rides his bike, the altitude declines by 10m (meters)
let m represent how many meters the altitude declined.
If there is a positive number (ex. 2) multiplied by a negative number (-2), The result will be negative (-4) and vice-versa.
Same goes with division. positive number (4) divided by negative number (-2), the result will be a negative quotient.
Therefore, the answer would be -60m, or -60 meters.