W, X, Y, Z are integers. The expression X - Y - Z is even and the expression Y - Z - W is odd. If X is even what must be true?
Answers.
A) U
B) W
C) E
D) H
E) R
Sol: X is even so Y, Z both are even or both are odd.   Now Y - Z in both cases even. So (Y - Z ) - W = odd happens only when w is odd   Ans: W is odd   Answer:W
<result>B</result>
W, X, Y, Z are integers. The expression X - Y - Z is even and the expression Y - Z - W is odd. If X is even what must be true?