the average age of 40 students in a class is 10 years . if teacher ' s age is also included then average increases 1 year then find the teacher ' s age ?
"total age of 50 students = 40 * 10 = 400 total age of 51 persons = 41 * 11 = 451 age of teacher = 451 - 400 = 51 years answer is d"
subtract(add(add(multiply(40, 10), 1), 40), multiply(40, 10))