5/5-4/5

To simplify the expression \( \frac{5}{5} - \frac{4}{5} \):

1. Calculate \( \frac{5}{5} \): This equals \( 1 \).
2. The expression now looks like: \( 1 - \frac{4}{5} \).
3. To subtract \( \frac{4}{5} \) from \( 1 \), convert \( 1 \) to a fraction with the same denominator: \( 1 = \frac{5}{5} \).
4. Now the expression is: \( \frac{5}{5} - \frac{4}{5} = \frac{5 - 4}{5} \).

So, \( \frac{5}{5} - \frac{4}{5} = \frac{1}{5} \).

Therefore, the final answer is \( \frac{1}{5} \).