Find hcf of y-b, y²-b² and y²-2yb+b²​

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.

Which of these figures must be a rectangle?

Ethan purchased a container of sports drink that contains 300 calories. the label says that 80% of the calories are from carbohydrates. how many calories are from carbohydrates?