To find the standard form of something in scientific notation, we multiply both numbers. Since 10^-1 is our number with a base of 10, and it has a exponent of -1, we move the decimal place of the other number one to the left. So our answer is D, 0.665.
Seeing as there are 1582 sets of 100 people (158200 ÷ 100) multiplying 42 by 1582 should get you the answer. 1582 × 42 = 66444. 66444 people voted in that city.
