The expression you've provided is correct. To detail it a bit more:
- Dillon pays \( x \) dollars for the haircut.
- He gives a 15% tip on the cost of the haircut, which can be calculated as \( 0.15 \times x \).
- Therefore, the total cost can be expressed as:
\[ \text{Total Cost} = \text{Cost of Haircut} + \text{Tip} = x + 0.15x \]
- This can also be simplified:
\[ \text{Total Cost} = 1x + 0.15x = 1.15x \]
So, the total cost of the haircut including the tip is \( 1.15x \).