17. Given f(x) = e*-7, select the statement that is true.
A. f-'(x) = In x - 7
B. f-'(x) = In(x - 7)
c. f-'(x) = In x + 7
D. f-'(x) = In(x + 7)

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.