X,Y and Z can do a piece of work in 15 days. If X takes twice as much as Y and Z together and Y takes thrice as much as X and Z together, how long days will each take to finish a work.
1/x + 1/y + 1/z = 1/15
x = 2(y+z)
y = 3(x+z)
Hmmm. I suspect a typo.