doubt

Given that the question says that a constant sales mix is to be assumed, then the entries must be in the ratio of 20,000 to 14,000. Your answer therefore cannot possibly be correct. Of the four choices of answers, then if you check only the first and last are in the correct ratio. As I wrote before, assuming that you have found this question in a Revision Kit from one of the ACCA approved publishers, then you must have an answer with workings and you must ask about whatever it is in the workings that you are not clear about.

Yes but, if revenue to get target profit is $1361538 , 1361538 *20/34 (where sales mix is 20 : 14 ) should give me sales of full marathon isnt it? where am i going wrong > Answer says 1361538 * 110 / 152 and 1361538 * 42/152 i dont understand that 110 and 42

When is says the sales mix is 20:14, that is the number of people - that is not the same as the revenue (because they charge different prices). In terms of revenue, for 20 full marathons, the revenue is 20 x 55 = $1100 For 14 half marathons, the revenue is 14 x $30 = $420 So the revenue is in the ratio 1100:420 (or 110:42)