There are 4 quarts in a gallon. If the paint costs $24 per gallon, to find the cost per quart, you can divide the cost of the gallon by the number of quarts in a gallon.
\[ \text{Cost per quart} = \frac{\text{Cost per gallon}}{\text{Number of quarts per gallon}} = \frac{24}{4} = 6 \]
Therefore, the cost of the paint is $6 per quart.