Please help me with this question thank you!

Evaluate the expression for the given value of the variable 7a - 4a for a =8

Which statement about the annual percentage rate (apr) is not true?

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.