Question : Directions: By Interchanging the given two numbers which of the following equations will be correct?
7 and 4

Option 1: 4 – 7 + 6 ÷ 2 × 3 = 12

Option 2: 4 × 3 + 7 – 9 ÷ 3 = 20

Option 3: 7 + 4 × 2 – 6 ÷ 2 = 17

Option 4: 7 + 5 × 2 – 4 ÷ 1 = 9

Correct Answer: 4 – 7 + 6 ÷ 2 × 3 = 12

Solution : Let's check the options –
First option: 4 – 7 + 6 ÷ 2 × 3 = 12
On interchanging the numbers, we get –
⇒ 7 – 4 + 6 ÷ 2 × 3 = 12
Solving the L.H.S. of the equation –
= 7 – 4 + 6 ÷ 2 × 3
= 7 – 4 + 3 × 3
= 7 – 4 + 9
= 16 – 4
= 12
Second option: 4 × 3 + 7 – 9 ÷ 3 = 20
On interchanging the numbers, we get –
⇒ 7 × 3 + 4 – 9 ÷ 3 = 20
Solving the L.H.S. of the equation –
= 7 × 3 + 4 – 9 ÷ 3
= 7 × 3 + 4 – 3
= 21 + 4 – 3
= 25 – 3
= 22 ≠ 20
Third option: 7 + 4 × 2 – 6 ÷ 2 = 17
On interchanging the numbers, we get –
⇒ 4 + 7 × 2 – 6 ÷ 2 = 17
Solving the L.H.S. of the equation –
= 4 + 7 × 2 – 6 ÷ 2
= 4 + 7 × 2 – 3
= 4 + 14 – 3
= 18 – 3
= 15 ≠ 17
Fourth option: 7 + 5 × 2 – 4 ÷ 1 = 9
On interchanging the numbers, we get –
⇒ 4 + 5 × 2 – 7 ÷ 1 = 9
Solving the L.H.S. of the equation –
= 4 + 5 × 2 – 7 ÷ 1
= 4 + 5 × 2 – 7
= 4 + 10 – 7
= 14 – 7
= 7 ≠ 9

So, only the first option satisfies the given equation. Hence, the first option is correct.