Problem: the average marks of 20 students in a class is 100 . but a student mark is wrongly noted as 50 instead of 10 then find the correct average marks ?
Rationale: "correct avg marks = 100 + ( 10 - 50 ) / 20 avg = 100 - 2 = 98 answer is c"
annotated_formula: divide(add(subtract(multiply(100, 20), 50), 10), 20)