Please help.

Describe all the numbers that when rounded to the nearest thousand are 645,000

Simplify (1/2)4th power a. (1/16) b.(1/8) c.(1/4)

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.