Consider the following : A + B means A is the son of B. A - B means A is the wife of B. What does the expression P + R - Q mean?

(a) Q is the son of P.
(b) Q is the wife of P.
(c) Q is the father of P. ✓ UPSC's answer
(d) None of the above

Why the answer is (c)

• The expression is P + R - Q, which must be evaluated from left to right based on the given definitions.

• First, 'P + R' means P is the son of R, establishing that R is the parent of P.

• Next, 'R - Q' means R is the wife of Q, establishing that Q is the husband of R.

• Combining these relationships, Q is the husband of R, and R is the parent of P.

• Therefore, Q is the father of P, as he is the male parent of P.

• This matches option (c).

Why the other options are wrong

(a) Q is the son of P.: Q is the father of P, not the son, as Q is the husband of P's parent R.
(b) Q is the wife of P.: Q is the father of P, not the wife, as Q is the husband of R.
(d) None of the above: Option (c) correctly identifies Q as the father of P, so 'None of the above' is incorrect.

Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2017, held on 18 June 2017. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.