How many years old will Fred be y years from now?

VERITAS PREP OFFICIAL SOLUTION:

Question Type: What Is the Value? This question asks how old Fred will be in y years.

Given information from the question stem: This question is asking for a specific number for the age that Fred will be y years from now. You can represent that as F + y.

Statement 1: Doris is 12 years older than Fred can be written “F + 12 = D.” This is clearly not sufficient to determine Fred’s age now or in the future. Eliminate
choices A and D.

Statement 2: The sum of the ages of Doris and Fred is y years can be written “F + D = y.” This statement only consists of three variables without any actual numbers, so it cannot give us a specific age for Doris or for Fred. This is not sufficient, so eliminate choice B.

Together: If you take both statements together you can use the second equation “F+D = y” and substitute “F+12” for D. This yields the equation “F + F + 12 = y.” Without knowing either what y is or what F is this equation cannot be solved, as it is one equation with two variables.

The answer is E.