To find the cost of one pencil using the equation \( y = 0.19x \), you need to set \( x = 1 \) (since \( x \) represents the number of pencils).
Substituting \( x = 1 \) into the equation:
\[ y = 0.19 \times 1 = 0.19 \]
So, the cost for one pencil is $0.19.