Question

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

Answer 1

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