How to find the constraints and maximum profit.?

Question: Han is an artist who specializes in geometric designs. he is trying to get ready for a fair next week. han paints both water colors and pastels (w= watercolors and p=pastels). each take same amoutn of time to paint. he has enough time to paint 16 at max. the materials for pastel will cost him 5$ and the materials for watercolors will cost him 15$. he was 180$ to spend on materials. he makes a profit of 40$ on each pastel and a profit of 1004 on each watercolor.