What will come in the place of the question mark (?) in the following equation, if ‘+’ and‘ב are interchanged and ‘−’ and ‘÷’ are interchanged?

51 ÷ 6 + 9 × 84 − 4 = ?​​​

Given: 51 ÷ 6 + 9 × 84 − 4 = ?

Given equation is solve by BODMAS rule.

​$$\begin{array}{|c|c|} \hline\textbf{Operation preference wise} & \textbf{Symbol} \\\hline\text{Brackets} &[],{}, () \\ \hline \text{Orders, of} & (power), √ (root) , of \\ \hline \text{Division}& ÷ \\ \hline \text{Multiplication} & × \\ \hline \text{Addition} & + \\ \hline \text{Subtraction} & - \\\hline\end{array}$$​

New equation: 51 - 6 × 9 + 84 ÷ 4 = ?

51 - 6 × 9 + 21 = ?

51 - 54 + 21 = ?

72 - 54  = ?

? = 18

Thus, correct option is (c).