Suraj has a certain average of runs for 8 innings. In the 9th innings he scores 90 runs thereby increasing his average by 6 runs. What is his average after the 9th innings?
Choose the correct option: A) 42 B) 64 C) 36 D) 72 E) 27

Rationale: "to improve his average by 6 runs per innings he has to contribute 8 x 6 = 48 runs for the previous 8 innings . thus , the average after the 9 th innings = 90 - 48 = 42 . answer : a"
Answer: A