Ed and Flora drive at constant speeds toward each other on a highway. Ed drives at a constant speed of 31 km per hour. At a certain time they pass by each other, and then keep driving away from each other, maintaining their constant speeds. If Ed is 120 km away from Flora at 6 am, and also 120 km away from Flora at 11 am, then how fast is Flora driving (in kilometers per hour)?  Options.
A) 13
B) 15
C) 17
D) 19
E) 21
Ed and Flora complete 240 km / 5 hours = 48 km/hour   Flora's speed is 48-31= 
<gadget id="calculator">48-31</gadget>
<output>17</output>
17 km/hour   The answer is 17.
<result>C</result>
Ed and Flora drive at constant speeds toward each other on a highway. Ed drives at a constant speed of 31 km per hour. At a certain time they pass by each other, and then keep driving away from each other, maintaining their constant speeds. If Ed is 120 km away from Flora at 6 am, and also 120 km away from Flora at 11 am, then how fast is Flora driving (in kilometers per hour)?