If X-Y = 2X-2Z, X-2Y = 4Z and X+Y+Z = 21, what is the value of Y/Z?	Choose the correct choice from the following choices.
A) -4.5.
B) -2.
C) -1.7.
D) -0.667.
E) 2.5.
X-Y = 2X-2Z   Y= -X+2Z---------- 1   X-2Y = 4Z   X-4Z= 2Y--------- 2   Adding equation 1 from equation 2   -2Z= 3Y   Y/Z= -0.667   -0.667. is the answer
<result>D</result>
If X-Y = 2X-2Z, X-2Y = 4Z and X+Y+Z = 21, what is the value of Y/Z?