∠a is an obtuse angle. a. the argument is valid by the law of syllogism. b. the argument is not valid because the conclusion does not follow from the premises. c. the argument is not valid because the premises are not true. d. the argument is valid by the law of detachment

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.