2/4-3

To solve the expression \( \frac{2}{4} - 3 \):

1. First, simplify \( \frac{2}{4} \) which equals \( \frac{1}{2} \).
2. Now the expression becomes \( \frac{1}{2} - 3 \).
3. To subtract 3, convert 3 into a fraction with a common denominator of 2: \( 3 = \frac{6}{2} \).
4. Now subtract: \( \frac{1}{2} - \frac{6}{2} = \frac{1 - 6}{2} = \frac{-5}{2} \).

So, \( \frac{2}{4} - 3 = -\frac{5}{2} \).