Problem: the average age of 36 students in a group is 14 years . when teacher ' s age is included to it , the average increases by one . find out the teacher ' s age in years ?
Rationale: "average age of 36 students in a group is 14 sum of the ages of 36 students = 36 × 14 when teacher ' s age is included to it , the average increases by one = > average = 15 sum of the ages of 36 students and the teacher = 37 × 15 hence teachers age = 37 × 15 - 36 × 14 = 37 × 15 - 14 ( 37 - 1 ) = 37 × 15 - 37 × 14 + 14 = 37 ( 15 - 14 ) + 14 = 37 + 14 = 51 answer is e ."
annotated_formula: add(36, const_1)