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

63 + 5 ÷ 35 - 7 × 21 = 23

Given equation : 63 + 5 ÷ 35 - 7 × 21 = 23

According to the question, after interchanging the mathematical signs:

So,

• Option - (1) : ÷ and ×

63 + 5 ÷ 35 - 7 × 21 = 23 ⇒ 63 + 5 × 35 - 7 ÷ 21 = 23

63 + 5 × 35 - 0.33 = 23

63 + 175 - 0.33 = 23

238 - 0.33 = 23

237.67 ≠ 23 (LHS ≠ RHS)

• Option - (2) : × and  +

63 + 5 ÷ 35 - 7 × 21 = 23 ⇒ 63 × 5 ÷ 35 - 7 + 21 = 23

63 × 0.14 - 7 + 21 = 23

9 + 21 - 7 = 23

30 - 7 = 23

23 = 23 (LHS = RHS)

• Option - (3) : ÷ and +

63 + 5 ÷ 35 - 7 × 21 = 23 ⇒ 63 ÷ 5 + 35 - 7 × 21 = 23

12.6 + 35 - 7 × 21 = 23

12.6 + 35 - 147 = 23

47.6 - 147 = 23

-99.4 ≠ 23 (LHS ≠ RHS)

• Option - (4) :  + and - 

63 + 5 ÷ 35 - 7 × 21 = 23 ⇒ 63 - 5 ÷ 35 + 7 × 21 = 23

63 - 0.14 + 7 × 21 = 23

63 + 147 - 0.14 = 23

210 - 0.14 = 23

209.86 ≠ 23 (LHS ≠ RHS)