Hi can you pls help me understand this and answer all 4? Pls explain what formulas you used and how to solve them. Thank you!

Write your answer in scientific notation. Keep exactly two decimals and use an asterisk to represent your multiplication symbol. Calculate the frequency of an EM wave with a wavelength of 1.98x1013. Calculate the wavelength of an EM wave with a frequency of 7.08x10-7. A lens produces an image 1.75 m tall using an object that is 2.31 m tall. What is the magnification of the lens? A lens with a magnification of 3.28 is used to look at an image that appears 0.82 m from the lens. How far away is the actual object form the lens