2. Era major divisions of geologic time within each era; identified by changes in the fossil record.

3. Eon: longest interval of geologic time.

4. Prokaryotic: a simple cell that lacks complex internal structures, e.g., bacterial cells.

5. Era: major divisions of geologic time within each eon; identified by major changes in the fossil record

6. Stromatolites: fossil mounds made of ancient
photosynthetic bacteria.

In the given word problem, we are asked to determine the distance the man traveled by plane. Let's assign variables to the distances:

x = miles traveled by automobile
9x = miles traveled by airplane

The problem states that the total trip was 600 miles in length, so we can write the equation:

x + 9x = 600

Simplifying the equation:

10x = 600

Now, we can solve for x by dividing both sides of the equation by 10:

x = 600 / 10
x = 60

So, the man traveled 60 miles by automobile (x), and to find the distance traveled by plane, we can substitute the value of x into the expression for airplane travel:

9x = 9 * 60 = 540

Therefore, the man traveled 540 miles by plane.

The sentence demonstrates the multiplicative identity is: (1/2 x 2 = 1).

10 - N = 8 + N represents "the difference between ten and a number is the sum of eight and a number".

The sentence demonstrates the multiplicative identity is: (1/2 x 2 = 1).