0.00048 ÷ (6 × 10-4) should be rewritten as 0.00048 ÷ (6 × 10^(-4) ). The symbol " ^ " denotes exponentiation. Without parentheses here, it appears that you want to subtract 4 from 10, which is inappropriate.
First focus on the " (6 × 10^(-4) )" This is equivalent to 6 / (10^4). To divide 0.00048 by 6 / (10^4), invert the divisor and then multiply:
0.00048 * (10^4 / 6) = 0.00008*10^4, or 8*10^(-5)*10^(4) = 8*10^(-1) = 8/10 = 0.8.
Note that all of the possible answer choices need to be re-written. 10-1, for example, must be re-written as 10^(-1).
