Question

Which two signs should be interchanged in the following equation to make it correct?

42 ÷ 7 + 12 × 2 – 36 = 18

1. ÷ and ×
2. + and ×
3. + and -
4. × and -

Answer 1

Correct Answer - Option 3 : + and -

By checking the options :

1) ÷ and ×

Given expression: 42 ÷ 7 + 12 × 2 – 36 = 18

After interchanging the symbol according to the option,

42 × 7 + 12 ÷ 2 – 36 = 18

= 294 + 6 – 36 = 18

= 300 – 36 = 18

= 264 ≠ 18

2) + and ×

Given expression: 42 ÷ 7 + 12 × 2 – 36 = 18

After interchanging the symbol according to the option,

42 ÷ 7 × 12 + 2 – 36 = 18

⇒6 × 12 + 2 – 36 = 18

⇒ 72 + 2 – 36 = 18

⇒74 – 36 = 18

⇒ 38 ≠ 18

3) + and –

Given expression: 42 ÷ 7 + 12 × 2 – 36 = 18

After interchanging the symbol according to the option.

42 ÷ 7 - 12 × 2 + 36

⇒ 6 – 24 + 36 = 18

⇒ 42 – 24 = 18

⇒ 18 = 18

4) × and –

Given expression: 42 ÷ 7 + 12 × 2 – 36 = 18

After interchanging the symbol according to the option,

42 ÷ 7 + 12 – 2 × 36 = 18

⇒6 + 12 – 72 = 18

⇒ 18 – 72 = 18

⇒ -54 ≠ 18

Hence, ‘+ and –’ is the correct answer.