If there are 10 parallelograms, then there are 20 triangles in the picture. Each parallelogram is divided into 2 triangles, so the total number of triangles is 10 parallelograms × 2 triangles per parallelogram = 20 triangles.
If the collection is expanded to 20 parallelograms with the same ratio, then each parallelogram will still be divided into 2 triangles. So the total number of triangles in the expanded collection will be:
20 parallelograms × 2 triangles per parallelogram = 40 triangles
Therefore, if the collection is expanded to 20 parallelograms with the same ratio, there will be 40 triangles in the picture.