I Am Studing For The At-sat Test And I Ran In To This Question On The Pre-test. Can Anyone Figure This Out?

If a plane was decending at 500 feet per second from an attitude of 18,000 feet traveling at 165MPH, how many miles would the plane have to traveled as it decended to 14,500 feet? (Air Traffic Control Career Prep) A. 25 B. 19 C. 12 D. 30 According to the book the answer is B. [...]