If a person's eye level is h meters above sea level and he can see d kilometers to the horizon, then d=3.6√ℎ. Suppose the person can see 13.5 kilometers to the horizon. What is the height of his eye level above sea level?

Lizette is training for a marathon. at 7: 00 she left her house and ran until 8: 30, then she walked until 11: 30. she covered a total distance of 18 miles. her running speed was six miles per hour faster than her walking speed. find her running and walking speeds in miles per hour.