In certain year in Country C, x sets of twins and y sets of triplets were born. If there were z total babies born in Country C in this year, and x and y were both greater than 0, which of the following represents the fraction T of all babies born who were NOT part of a set of twins or triplets?
Choose the correct choice from the following answers:
A) z - 2x - 3y
B) (2x+3y)/z
C) (x+y)/z
D) 1 - (2x+3y)/z
E) 1 - (x+y)/z
X set of twins implies 2x babies of twin category.   Y set of triplets means 3y babies of triplet category.   Let K be the babies other than twin or triplet category.   Total babies = z = 2x+3y+k.   or K=Z-(2x+3y)   =&gt; Fraction of babies other than twin or triplet categories = K/Z = Z-(2x+3y)/Z.   T= 1- (2x+3y)/Z. Hence answer is 1 - (2x+3y)/z.
<result>D</result>
In certain year in Country C, x sets of twins and y sets of triplets were born. If there were z total babies born in Country C in this year, and x and y were both greater than 0, which of the following represents the fraction T of all babies born who were NOT part of a set of twins or triplets?