4. In a certain code language, '+' represents 'x', '-' represents '+', 'x' represents '÷' and '÷' represents '-'. What is the answer to the following question? 72 x 9 - 14 + 2 = ?
7. In a certain code language, '+' represents 'x', '-' represents '+', 'x' represents '÷' and '÷' represents '-'. What is the answer to the following question? 25 + 10 ÷ 240 x 16 = ?
10. In a certain code language, 'x' represents '+', '÷' represents 'x', '-' represents '÷' and '+' represents '-'. Find out the answer to the following question. 5 + 10 x 21 ÷ 5 - 15 = ?