4.84 times ten to the fifth power plus 3.9 times 10 to the second power plus 8.91 times 10 to the 7th power

Okay, so you didn't really put anything for me to know what you wanted to solve, so I'm going to assume this is Scientific Notation:

We have:

10^5 = 100,000 x 4.84 would be: 484,000

10^2 = 100 x 3.9 would be: 390

10^7 = 10,000,000 x 8.91 would be: 89,100,000