What will come in place of the question mark (?) in the following equation if '+' and '$\times$ ' are interchanged and '-' and '$÷$ ' are interchanged?
$$16-4+7\times 8÷1=?$$

Given original equation:
$$16-4+7\times 8÷1=?$$
Interchanging the signs as instructed:$-$ becomes $÷$$+$ becomes $\times$$\times$ becomes $+$$÷$ becomes $-$ Substituting the new signs into the equation:
$$16÷4\times 7+8-1=?$$
Now, apply the BODMAS rule:Division: $16÷4=4$ $
$\text{Equation becomes: }4\times 7+8-1=?$$Multiplication:$ 4 \times 7 = 28
$\text{Equation becomes: } 28 + 8 - 1 = ?
Addition: $28+8=36$ $
$\text{Equation becomes: }36-1=?$$Subtraction:$ 36 - 1 = 35$Therefore,$? = 35$.