the average age of 21 students of a class is 21 years . out of these , the average age of 5 students is 14 years and that of the other 9 students is 16 years , the age of the 21 th student is
"explanation : age of the 21 th student = [ 21 * 21 - ( 14 * 5 + 16 * 9 ) ] = ( 378 - 214 ) = 164 years . answer : a"
subtract(multiply(21, 21), add(multiply(5, 14), multiply(9, 16)))