I'm not sure what you mean by the percentages, because ideally, you should be providing a 50/50 split for both texts (as they are both equally as important in creating your essay).
So with 3 paragraphs, you're going to be using an integrated structure, whereby each paragraph explores a similar theme. You can do this in 2 ways, considering you will need a minimum of 4 quotes/pieces of evidence per paragraph:
Method 1 (alternating method):
Text 1: Evidence 1
Text 2: Evidence 1
Text 1: Evidence 2
Text 2: Evidence 2
Method 2 (2 blocks):
Text 1: Evidence 1 & 2
Text 2: Evidence 1 & 2
If you decided to change your mind and have 4 body paragraphs, you would be using a divided structure. There's more information on this as well as the 3 paragraph method in the link here -->
https://www.matrix.edu.au/how-to-write-a-comparative-essay-module-a-textual-conversations/
