Need help with a caesar cipher project: what excel formulas to use?

Need help finding the following: (see attachment)

A formula to calculate the frequency percentage for each letter (i.e. the letter frequency divided by the number of ciphertext characters). Verify that the sum of the frequency percentages is 100%.

Manually compare the frequency percentages from Column J with those from the Frequency Distribution Table, to predict the translation factor needed to decrypt the Caesar cipher. Enter the translation factor in cell C1.

Create a table in cells A3 thru C28 containing the letters of the alphabet, their numeric equivalents, and a formula to calculate the translated numeric equivalent

Enter a formula in cells B31 thru B298 to decrypt the ciphertext message.


I used COUNTIF for the letter frequency. I'm not asking for answers: but maybe some guidence on what excel formulas to use in each cell?