In this picture, consider dotted line as the mirror and complete the figure using the mirror image on the right side. What is the shape of the complete figure after adding the mirror image?
Daw bought a total of 21 hens and ducks. He got a discount of ฿0.40 for each hen and a discount of ฿1.10 for each duck. He saved ฿15.40 in total. How many hens did he buy?