In every number, set every digit to zero that is not 8. Then look at the question again.
"Which of these lengths has 1/10 the value of 8.0?"
- A. 800
- B. 0.08
- C. 80
- D. 0.80
We hope the answer D is obvious to you.
... 0.80 = (1/10)×8.0
___
The appropriate choice is ...
... D. 209.86
Let g be the number of grandchildren, and d be the number of dogs. They both have only one head, so the number of heads is

Grandchildren have 2 legs, while dogs have 4. So, the total number of legs is

From the first equation (the one for the heads) we can derive

Substitute this into the second to get

So, there are 9 dogs and (from the first equation
