Answer:
x = (10-6)/2 = 2
Step-by-step explanation:
This is not German and in Germany you would use the metric system, not your feet to measure a wall but here is the answer to your math problem:
When the painting is 6 feet wide and your wall is 10 feet wide, the remaining space on the wall is 10-6 = 4 feet. When you want to center the painting on the wall, the space on each side must be equal, therefore divide by 2.