Answer:
7.4 x 10^7
Explanation:
3.98 x 10^8 - 3.24 x 10^8 = 0.74 x 10^8 (not scientific notation, because it isn't full number)
0.74 x 10^8 ---> 7.4 x 10^7
- got seven by counting the spaces it moved over (right decrease, while left increases)
5.2m questions
6.7m answers