Q is as much younger than R as he is older than T. If the sum of the ages of R and T is 50 years, what is definitely the difference between R and Q's age?

The difference of age b/w R and Q = The difference of age b/w Q and T.
Sum of age of R and T is 50 i.e. (R + T) = 50.

R - Q = Q - T
=> (R + T) = 2Q
Now given that,
(R + T) = 50
So, 50 = 2Q and therefore Q = 25.

Question is (R - Q) = ?
Here we know the value (age) of Q (25), but we don't know the age of R.
Therefore, (R-Q) cannot be determined