In the equation \( y = 0.19x \), the variable \( x \) represents the number of pencils. To find the cost for one pencil, you substitute \( x = 1 \) into the equation:
\[ y = 0.19 \cdot 1 = 0.19 \]
So, the cost for one pencil is \( y = 0.19 \) dollars, or 19 cents.