When expressed as a repeating decimal, the fraction
1
7
is written as
0.142857142857
…
(The 6 digits 142857 continue to repeat.) The digit in the third position to the right of the decimal point is 2. In which one of the following positions to the right of the decimal point will there also be a 2?

We don't see the menu of answers.  Since the period of the repeating part is 6, we'll see a two at positions:

3, 9, 15, 21, 27, 33, 39, ..., 6n-3

the 8 in 8,420 is in the thousands place so it's value is 8 thousand.

the 8 in 6,870 is in the hundreds place so it's value is 8 hundred.

divide 8000 by 800 to find the answer:

8000 / 800 = 10

the 8 in 8,420 is 10 times greater than the 8 in 6,870