A lemonade stand sold only small and large cups of lemonade on Tuesday. 2/5 of the cups sold were small and the rest were large. If the large cups were sold for 7/6 as much as the small cups, what fraction of Tuesday's total revenue was from the sale of large cups?	Choose the correct answer:
A) ( a ) 7 / 16  B) ( b ) 7 / 11  C) ( c ) 10 / 21  D) ( d ) 17 / 35  E) ( e ) 1 / 2

Rationale: "a simpler way i guess would be to think that in total 5 cups were sold . out of which 2 are small and 3 are large . now let the small ones cost $ 6 . so the large ones would cost $ 7 . so , 2 * 6 = 12 and 3 * 7 = 21 . total revenue was 12 + 21 = 33 and large cup sales as found above is 21 therefore answer is 21 / 33 i . e 7 / 11 b"
Answer: B