A.) 8.3 x 10^1
The rules of scientific notation are similar to the laws of exponents (if u know them) in the sense that: 10^a / 10^b is equal to 10^(a-b)
So, 10^4 / 10^2 = 10^(4-2) = 10^2.
Then, you divide 2.49 by 3.0 and you get 0.83. But correct scientific notation requires the decimal to be one digit right of the first significant digit, so 0.83 becomes 8.3 and when you change the decimal place you also have to change the scientific notation. So 0.83 x 10^2 becomes 8.3 x 10^1 because we are moving the decimal place to the right. When the decimal moves to the right the power of ten decreases and when the decimal moves to the left it increases.
Hope this helped!