The overall age of X and Y is 15 year greater than the overall age of Y and Z. Z is how many decades younger that X?	Select:	A) 11	B) 15	C) 12	D) 17	E) 19
15   15   (X + Y) â€“ (Y + Z) = 15   X â€“ Z = 15
<result>B</result>
The overall age of X and Y is 15 year greater than the overall age of Y and Z. Z is how many decades younger that X?