Answer: B: The temperature is 20 degrees below zero and C: A driver's speed decreases by 20 miles per hour.
Step-by-step explanation: B: If the temperature is 20 degrees BELOW zero then that would be -20. If it was above, then it would be just 20. C: If the drivers speed DECREASES by 20 then that would be -20, since its going down. Hope this helps! :)