Which algebraic expression is a polynomial with a degree of 3?

A) 4x3 – StartFraction 2 Over x EndFraction

B) 2y3 + 5y2 – 5y

C) 3y3 – StartRoot 4 y EndRoot

D) –xyStartRoot 6 EndRoot

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.