I have a test tomorrow and I didn’t study cuz I have no friends this would help. I’m sorry if u can’t do it I understand...:(.but pls help me

Will give brainliest what is the value of x? enter your answer in the box.

What is the number 321,000,000 in scientific notation? also what is the number? ?

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.