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 answers
A) -4.5. B) -2. C) -1.7. D) 3. E) 2.5.
Given : X+Y = 2X-2Z, --&gt; eq 1   X-2Y = 4Z --&gt; eq 2   X+Y+Z = 21 --&gt;eq 3.   Now we are asked to find the value of Y/Z.   Now let choose some option randomly,   Take C , which is 3, I randomly chose this value as it is positive :)   Y/Z = 3 , this is the value we need to get.   Then Y = 3Z -- eq 4   Sub this in eq 1.   X + 3Z = 2X - 2Z   =&gt; X = 5Z --&gt;eq 5.   Sub X and Y value in eq 3.   5Z + 3Z + Z = 21   =&gt; Z = 21/9. Now sub this value to get Y , we get Y = 21/3.   Then Y/Z = 21/3 / 21/9 = we get 3 again. So this option is correct.   Answer: option -1.7. is correct.
<result>C</result>
If X+Y = 2X-2Z, X-2Y = 4Z and X+Y+Z = 21, what is the value of Y/Z?