Answer:
521 nm
Explanation:
Given the values and units we are given, I'm assuming 5.76*10^14 Hz is frequency.
The formula to use here is λ * υ = c, where λ is wavelength, υ is frequency, and c is the speed of light.
λ = 
8 x 10^8 = 800,000,000
In Scientific Notation, your goal is to get your the number you're multiplying by 10 (8 in this case) to be between 0 and 10. Therefore, you would NOT have 80 x 10^7 because 80 is not between 0 and 10.
So that we do not contaminate it with microorganisms or garbage or other human stuff.