x + y + z = 50
y + 10 = x, solving for y, y = x - 10
x = 2z, solving for z, z = x/2
Substituting for y and z,
x + x - 10 + x/2 = 50
(5/2)x - 10 = 50
(5/2)x = 60
x = (2/5) * 60 = 24
y = x - 10 = 24 - 10 = 14
Z = x/2 = 24/2 = 12
Checking:
x + y + z = 50, 24 + 14 + 12 = 50, 50 = 50. Solution meets the initial constraint.