sir if you read the march 2019 examiner’s report first section A question, what in the question was different from the usual questions we do, that should have indicated us that it was not a normal weighted average C/S ratio question?
Using a weighted average CS ratio applies only to multiple products that are sold in the same ratio whatever the total number of units (as I explain in my lectures, which it appears you have not bothered to watch).
There is no mention here of that being the case and it is a basic key factor analysis question (combined with the most basic knowledge of what ‘breakeven’ means).