adding/subtracting scientific notation

The US spends 1.02x10⁴ dollars on EACH student per year. There are 7.6x10⁷ students in the US. About how much money total is spent on students per year?

• 7.752 x 10¹¹

• 7.752 x 10²⁸

• 8.62 x 10¹¹

• 8.62 x 10²⁸

In 2012, NYC’s population was about 8.1 × 10⁶ and Los Angeles' population was about 3.8 × 10⁶. What is the population of these two cities combined?

*THE FIRST FACTOR HAS TO BE BETWEEN 1 - 9.9

• 1.19 x 10^-7

• 1.19 x 10⁷

• 11.9 x 10⁶

• 1.19 x 10⁶