Answer: 180*5=900
Explanation:
1) Start from the middle triangle and draw 2 lines connecting the edges to the bottom 2 angles. This should result in the crown splitting into 3 sections.
2) Go to the triangles on each side and connect them to the middle triangle. It should result in the crown having 5 triangles.
3) Multiply the 5 triangles by 180 (the angle sum of a triangle) to get 900.
Crown after all the lines are drawn: