The average age of 40 students of a class is 16 years. If the average age of 24 students is 15.5 years and that of the 15 students is 16 2⁄3 years, then the age of 40th student is
In a certain code language, '-' represents 'x', '÷' represents '+', '+' represents '÷' and 'x' represents '-'. Find out the answer to the following question.