Answer:
9
Explanation:
If the ramp had a slope of 1, the answer would be 6. However, because it has a slope of 2/3, the ramp travels 3/2 times the amount it would if the slope was 1, and moreover so would the ball. Therefore, by multiplying 2/3 by 3/2, the ball traveled 9 feet. I hope this helps! I would call this subject general geometry.