A shopkeeper purchased 15 kg of variety A rice at X per kg and 10 kg of variety B rice at ‘X+ 5’ per kg. The shopkeeper sold the whole quantity of variety A rice at 10% profit and that of variety B rice at 20% profit. The total selling price of variety A rice was 30/- more than that of variety B rice. Had the two varieties been mixed and sold at an overall profit of 20%, what would have been the selling price of the mixture per kg?