How many 3-stripe flags can be made of materials of 5 different colors if the stripes are to be all different?

Red, blue, black, green, yellow

1. red blue black

2. red blue green

3. red blue yellow

4. red black green

5. red black yellow

6. red yellow green

7. blue black green

8. blue black yellow

9. blue green yellow

10. yellow green black

there are 10 combinations