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

39 ÷ 6 – 3 × 9 + 4 = ?

What will come in the place of the question mark ‘(?)’ in the following equation, if ‘+’ and ‘−’ are interchanged and ‘×’ and ‘÷’ are interchanged?
116 ÷ 5 − 423 × 3 + 13 = ?​

Which of the following equations is correct when the numbers 12 and 6 are interchanged and the signs ÷ and + are interchanged?

Which of the following equations is correct when the numbers 3 and 9 are interchanged and the signs - and × are interchanged?

If 'p' means '×', 'q' means '-', 'r' means '÷' and 's' means '+', then which of the following equation is NOT correct?
I. 44 s 51 r 17 q 20 p 4 = -31
II. 57 r 19 s 5 p 10 q 18 = 35

If 'P' stands for 'x', 'Q' stands for '÷', 'R' stands for '-' and 'S' stands for '+', then the resultant of which of the following would be 57?