If X+Y = 2X+Z, X-2Y = 4Z and X+Y+Z = 21, what is the value of Y/Z?  Choose the correct choice from the following options
A) - 4.5 .  B) - 2 .  C) - 1.7 .  D) 3 .  E) 6 .

Rationale: x + y = 2 x + 2 z y = x + 2 z - - - - - - - - - - 1 x - 2 y = 4 z x - 4 z = 2 y - - - - - - - - - 2 subtracting equation 1 from equation 2 - 6 z = y y / z = - 6 e is the answer
Answer: E