I hope that there is no a mistake my operations. I didn't check my solution.
Solution: clearly x, y,z are non-zero.
xy = 10x + 15y then, y = 10x/(x - 15) ... (1)
yz = 15y + 6z then, y = 6z/(z - 15) ... (2)
also we have zx = 30z + 50x ... (3)
from (1) and (2), we find 2zx = 75x - 45z ... (4)
by the equations (3), (4) we yields 21z = 5x ... (5)
let's solve (4) and (5) simultaneously. so, x = -180, z = 300/7. hence we find that y = 20/13.