Hi megaman64,
This is a question that will get asked over and over again, and in reality, there is no right answer. Different ratios exist for essentially any essay, and there is no predetermined ratio that is required in order to score top marks.
Having said that, some example ratios could include 50:25:25 or 60:20:20. Note that the general rule is; you should write approximately the same amount on each related text. If you were doing one related text, you would do a ratio such as 50:50 or 60:40. For your internal assessments, make sure you ask your teacher what they're looking for.
Nonetheless, the ratio is a non-issue. As long as the essay appears reasonably balanced to the marker, they will not notice. Markers do not sit and measure the ratio of related to core texts in essays, they mark an essay based on its merits. As long as your analysis throughout backs your thesis, answers the question and offers an insightful discussion to the module rubric, the ratio of texts shouldn't be a problem.
Regards,
Delta Education