In a certain code language, '-' represents'+', '+' represents 'x', 'x' represents '÷' and '÷'represents '-'. Find out the answer to the following question.
In a certain code language, '+' represents 'x', '-' represents '+', 'x' represents '÷' and '÷' represents '-'. What is the answer to the following question? 642 x 6 ÷ 25 + 4 = ?