Answer: The answer is 84 ways
Explanation: A house with a square floor plan is to have each of its outer four walls fin- ished with brick, stone, stucco, or wood. However, If no two adjacent outer walls are to have the same finish, there are 84 ways the house walls will be constructed. One of such way is brick on the front and back and also stone on the left and right.
Answer:
"In Brief. Sometime between 195,000 and 123,000 years ago, African Homo sapiens populations plummeted, thanks to cold, dry climate conditions that left much of the land uninhabitable. Everyone alive today is descended from people from a single region who survived this catastrophe."
Explanation:
i got it off google..hope it helps you.