In a certain code language, '+' represents 'x', '-' represents '+', 'x' represents '÷' and '÷' represents '-'. What is the answer to the following question? 56 ÷ 8 + 12 - 72 = ?
5. A*B means multiply A by B; A@B means divide A by B, A?B means add B to A and A=B means subtract B from A. Then find the value of 10*10 = 5*10 ? 50@10