Use multiplication to find 5% of 180 step by step

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.

Which geometric principle is used to justify the construction below?

Factor the gcf out of the polynomial 9x^6+6x^4+15x^3