Which two signs and numbers need to be interchanged to make the following equation correct?
(42 × 13) + (6 × 4) – (39 ÷ 3) = 105

Concept: interchange numbers and mathematical operators and solve as per BODMAS rule.

​$$\bold{Given:}(42 × 13) + (6 × 4) – (39 ÷ 3) = 105 \\ \ \\\begin{array}{|c|c|} \hline \textbf{Operation preference wise} & \textbf{Symbol} \\\hline Brackets &[],{}, () \\ \hline Orders, of & (power), √ (root) , of \\ \hline Division& ÷ \\ \hline Multiplication & × \\ \hline Addition & + \\ \hline Subtraction & - \\\hline \end{array}$$​​

​$$(39 × 13) - (6 × 4) + (42 ÷ 3) = 105\\ \ \\507 - 24 + 42 = 105\\ \ \\549 - 24 = 105\\ \ \\525\not=105$$​​

​$$(6 × 13) - (42 × 4) + (39 ÷ 3) = 105\\ \ \\78 - 168 + 13 = 105\\ \ \\91 - 168 = 105\\ \ \\- 77 \not=105$$​​

(42 × 3) - (6 × 4) + (39 ÷ 13) = 105

126  - 24 + 3 = 105

129 - 24 = 105

By option (d): 13 and 4, ÷ and −

(42 × 4) - (6 × 13) + (39 ÷ 3) = 105

168 - 78 + 13 = 105

181 - 78 = 105

103$$\not=$$105

Thus, correct option is (c).

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