the average age of a class of 20 students is 22 years . the average increased by 2 when the teacher ' s age also included . what is the age of the teacher ?
"if age of the teacher was 22 , average would not have changed . since average increased by 2 , age of the teacher = 19 + 22 × 1 = 44 answer : e"
subtract(multiply(add(20, 2), add(22, 2)), multiply(20, 22))