Answer
See below.
Work Step by Step
1. To prove the statement by contraposition, we need to show that:
if none of the two real numbers are less than 25, then the sum of the two numbers will not be less than 50.
2. Let $x, y$ be any real numbers with $x\ge25$ and $y\ge25$, we have $x+y\ge50$ which means that the sum of the two numbers will not be less than 50.
3. Thus, we can conclude that the statement in the exercise is true.