The grade point average of the entire class is 85. If the average of one third of the class is 97, what is the average of the rest of the class? Pick one.
A) 76 B) 77 C) 78 D) 79 E) 80

Rationale: "let x be the number of students in the class . let p be the average of the rest of the class . 85 x = ( 1 / 3 ) 97 x + ( 2 / 3 ) ( p ) x 255 = 97 + 2 p 2 p = 158 p = 79 . the answer is d ."
Answer: D