PLEASE HELP!! What is the height of the triangle?

If square root x = -7, then x= -49 true or false

When you answer this can you explain

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.