Question Arwin from Kaplan

Good evening! I'm trying to settle Q51 Arwin from Kaplan Exam Kit for year 2015. In the scenario, Sales revenue equal to 50,000. Cost of sales = 30,000 Sales revenue is expected to increase by 12% for the first year. And it is said that variable cost of sales makes up 85% of cost of sales. So, new revenue will be 56,000 (50,000*1,12). As for the VC it is said in the answer (85%* sales) = 28,560. Still, I can not understand, how did they get 28,560? Because, it this scenario means, that 85% of new level of sales we could not get 28,560. What I did, first I tried to calculate prior level of contribution: if COS = 30,000, then we get fixed cost 15% = 4,500. And VC = 30,000 - 4,500=25,500 So, contribution will be 50,000 - 25,500 = 24,500 Fixed costs won't change, and remain 4,500. So, I can calculate, that previously, VC represented 51% from Sales (25,500/50,000) and I may suppose, that the same proportion will be for the new year. 51%*56,000 = 28,560. This is the only logic I see. My question is, when it was written in the answer 85%* sales = 28,560 - what did they meant? Thank you in advance!