Maria is coloring in triangles, squares and circles using 3 colors (red, blue and yellow). If Maria only uses a color on each shape one time, how many different combinations can she make?

There are 3 shapes (triangle, square, circle) and 3 colors (red, blue, yellow).

Therefore, Maria can make 3! = 3 x 2 x 1 = 6 different combinations of shapes and colors.