2/5-1

To calculate \( \frac{2}{5} - 1 \), first convert 1 to a fraction with a denominator of 5:

\[ 1 = \frac{5}{5} \]

Now, subtract the two fractions:

\[ \frac{2}{5} - \frac{5}{5} = \frac{2 - 5}{5} = \frac{-3}{5} \]

So, \( \frac{2}{5} - 1 = \frac{-3}{5} \).