Which two signs should be interchanged to make the given equation correct?

87 × 2 − 80 ÷ 8 + 160 = 4

Logic: interchange mathematical operators and solve as per BODMAS rule.

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

Check option A,​​​+ and −​

87 × 2 − 80 ÷ 8 + 160 = 4

After interchanging,

87 × 2 + 80 ÷ 8 - 160 = 4

174 + 10 - 160 = 4

24≠4

So, its not correct option.

Check option B, ​​​​+ and =​

87 × 2 − 80 ÷ 8 + 160 = 4

After interchanging,

87 × 2 − 80 ÷ 8 = 160 + 4

174 − 10 = 164

Check option C,​​​+ and ×​

87 × 2 − 80 ÷ 8 + 160 = 4

After interchanging,

87 + 2 − 80 ÷ 8 × 160 = 4

89 − 10 × 160 = 4

89 − 1600 = 4

-1511≠4

So, its not correct option.

Check option D, ​​+ and ÷​

87 × 2 − 80 ÷ 8 + 160 = 4

After interchanging,

87 × 2 − 80 + 8 ÷ 160 = 4

Here, 8 is perfectly not divisible by 160.

So, its not correct option.

Thus, correct option is (b).