The overall age of X and Y is 18 year greater than the overall age of Y and Z. Z is how many decades younger that X?
Choose the correct choice from the following options
A) 11  B) 15  C) 12  D) 17  E) 18
18   18   (X + Y) â€“ (Y + Z) = 18   X â€“ Z = 18
<result>E</result>
The overall age of X and Y is 18 year greater than the overall age of Y and Z. Z is how many decades younger that X?