First, let's start by adding the first two terms: (3x - 8) + (2x + 5) = (3x + 2x) + (5 - 8) = 5x + (-3) = 5x - 3
Then we can combine this result with the third term: (5x - 3) - (4x - 8) = (5x - 4x) + (-3 - (-8)) = x + (-3 - (-8)) = x + 5
Therefore, the simplified expression is: x + 5.
The answer is therefore (E) x + 5.