for what value of k of the pair of equations 3 X + 4 Y + 2 is equals to zero and 9 X + 12 Y + K is equals to zero represents coincident lines ​

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.