The amount last month Calvin made from all the paintings sold at the art shows was $414.90
The first analyse the given information;
→ Small paints (lets call them ) sell for $25.80 Per Painting,
Thus 25.80s gives as the profit for number paints sold.
Large paints (lets call them ) sell for $56.25 Per Painting,
Thus, 56.25s gives as the profit for number paints sold.
Thus the total profit of all paintings sold would be;
= 56.25×6 + 25.80×3
= $414.90
Therefore, last month Calvin made $414.90 from all the paintings sold at the art shows.