Posted by Dale on Sunday, February 21, 2010 at 10:54pm.
Adam, Bill, Chris, and Dave each own one quarter of a company. Bill sells
2/3 of his shares to Dave. Adam sells 3/5 of his shares to Chris and the
rest to Dave. How much of the company does Dave own now?

Math  Reiny, Sunday, February 21, 2010 at 11:03pm
Let's say each one has $x
Dave gets (2/3)x from Bill and (2/5)x from Adam
So Dave now has x + (2/3)x + (2/5)x
= x(1 + 2/3 + 2/5) = (31/15)x
So now he owns [(31/15)x]/(4x)
31/60 of the company