It looks like your question is incomplete, but I'll try to infer the intended problem. Based on your question, it seems like the painter is mixing black and white paint to achieve a certain shade of gray. To determine how many cups of white paint are needed to make the same shade of gray as with the 18 cups of black paint, we would need a ratio or percentage indicating how the two colors are mixed.

Assuming this is a typical paint-mixing problem where gray is made by mixing black and white in a certain ratio, you might be looking for a formula like:

$\text{Total cups of paint} = \text{cups of black paint} + \text{cups of white paint}$

The shade of gray depends on the specific ratio between black and white. For example, if the ratio is 1:1 (equal parts black and white), then 18 cups of black would need 18 cups of white.

Could you clarify the ratio or provide more details about the mixing proportions?

Would you like further details or clarifications? Here are 5 related questions to expand on the concept:

1. What ratio of black to white paint is used to achieve the desired shade of gray?
2. How do different ratios of black and white affect the final color of the paint?
3. How does the volume of paint affect the coverage area for painting?
4. What is the method to calculate the amount of paint required for a given surface area?
5. How do you adjust paint mixtures to make a darker or lighter shade?

Tip: When mixing colors, always mix small amounts first to test the shade before scaling up!