Arun, Mini and Sherry work together to arrange a party. The time it takes them to do the work together is two and half hours hours less than Arun would have taken working alone, 5/6th of an hour less than what Mini would have taken alone. Also, Sherry takes double the time that Mini takes to do the work. How long did it take them to do these chores working together? (a) 20 minutes (b) 30 minutes (c) 40 minutes (d) 50 minutes .