$12:30$ - $40$ min = $11:50$ 
Lucy, Maria, and Anna have a meeting at $$12:30$$. Lucy\textquotesingle s walk takes $$10$$ minutes, Maria\textquotesingle s walk takes a quarter of an hour, and Anna\textquotesingle s walk takes $$40$$ 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) 
$$12:00$$ 
$$12:10$$ 
$$12:15$$ 
$$12:20$$ 
$$11:50$$ 