All you do is multiply 15 and 6 you get 90. then divide 90 by 9 and you get 10.
Answer: 
Step-by-step explanation:
1. If you join the top part and the bottom part of the figure, you obtain a sphere. Then, you must apply the formula for calculate the surface area of a sphere:

Where r is the radius (
)
2. Then:

3. The formula for calculate the suface area of the red part, which is a cylinder, is:

Where h is the height (h=32mm)
4. Then:

5. So, the total surface area is:
