Which of the following interchange of numbers and mathematical signs would make the given equation correct?
72 ÷ 8 × 9 − 36 + 20 = 80

 

The pattern followed here is:

Here, we have to interchange the numbers and mathematical signs that would make the given equation correct.

Let's check each option one by one.

Option 1) 20 and 80, × and +

After interchanging the number and sign we get the:

⇒ 72 ÷ 8 + 9 − 36 × 80 = 20

⇒ 9 + 9 - 36 × 80 = 20

⇒ 9 + 9 - 2880 = 20

⇒ 18 - 2880 = 20

⇒ -2862 ≠ 20

⇒ LHS ≠ RHS

Option 2) 9 and 36, × and ÷

After interchanging the number and sign we get the:

⇒ 72 × 8 ÷ 36 − 9 + 20 = 80

⇒ 72 × 0.222 - 9 +20 = 80

⇒ 15.84 - 9 + 20 = 80

⇒ 35.84 - 9 = 80

⇒ 26.84 ≠ 80

⇒ LHS ≠ RHS

Option 3) 36 and 72, ÷ and −

After interchanging the number and sign we get the:

⇒ 36 - 8 × 9 ÷ 72 + 20 = 80

⇒ 36 - 8 × 0.125 + 20 = 80

⇒ 36 - 1 + 20 = 80

⇒ 56 - 1 = 80

⇒ 55 ≠ 80

⇒ LHS ≠ RHS

Option 4) 8 and 9, + and −

⇒ 72 ÷ 9 × 8 + 36 - 20 = 80

⇒ 8 × 8 + 36 - 20 = 80

⇒ 64 + 36 - 20 = 80

⇒ 100 - 20 = 80

⇒ 80 = 80

⇒ LHS = RHS

Hence, the correct answer is "Option 4".