Please Help! I willl give braibliest! :) Could the value of x in the triangle below be 4, 6, 9, or 10?

The value of x could be ___.

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.