Find the perimeter of the triangle with vertices d(3, 4), e(8, 7), and f(5, 9). do not round before calculating the perimeter. after calculating the perimeter, round your answer to the nearest tenth.
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.