You're flying from Joint Base Lewis-McChord (JBLM) to an undisclosed location 39 km south and 222 km east. Mt. Rainier is located approximately 56 km east and 40 km south of JBLM. If you are flying at a constant speed of 800 km/hr, how long after you depart JBLM will you be the closest to Mt. Rainier?

______ minutes

So I worked it out and thought it would be 16 minutes, but I was wrong. Can someone help me?