The sum of the first n consecutive even numbers can be found using s=n2+n, where n/2. what is the value of n when the sum is 156?

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.