$12:30-40 min=11:50$ 
Lucy, Maria and Anna have a meeting at $$12:30$$. Lucy\textquotesingle s walk takes $$10$$ minutes, Maria\textquotesingle s a quarter of an hour, and Anna\textquotesingle s $$40$$ minutes. At what time must the person who needs the longest time to get to the meeting leave her house? (2006 Math Kangaroo Problem, Level 1-2, Question \#9) 

a: $$12:00$$ 
b: $$12:10$$ 
c: $$12:15$$ 
d: $$12:20$$ 
e: $$11:50$$ 