Question : Directions: Which two numbers must be interchanged to correct the following equation?
22 – 9 ÷ 5 + 10 × 1 = 29

Option 1: 22 and 10

Option 2: 5 and 1

Option 3: 10 and 9

Option 4: 5 and 10

Correct Answer: 10 and 9

Solution : Given:
22 – 9 ÷ 5 + 10 × 1 = 29

Let's check the options –
First options: 22 and 10
10 – 9 ÷ 5 + 22 × 1 = 29
On solving the L.H.S. of the given equation –
= 10 – 9 ÷ 5 + 22 × 1
= 10 – 1.8 + 22 × 1
= 10 – 1.8 + 22
= 30.2 ≠ 29
Second option: 5 and 1
22 – 9 ÷ 1 + 10 × 5 = 29
On solving the L.H.S. of the given equation –
= 22 – 9 ÷ 1 + 10 × 5
= 22 – 9 + 10 × 5
= 22 – 9 + 50
= 63 ≠ 29
Third option: 10 and 9
22 – 10 ÷ 5 + 9 × 1 = 29
On solving the L.H.S. of the given equation –
= 22 – 10 ÷ 5 + 9 × 1
= 22 – 2 + 9 × 1
= 22 – 2 + 9
= 29
Fourth option: 5 and 10
22 – 9 ÷ 10 + 5 × 1 = 29
On solving the L.H.S. of the given equation –
= 22 – 9 ÷ 10 + 5 × 1
= 22 – 0.9 + 5 × 1
= 22 – 0.9 + 5
= 26.1 ≠ 29

So, the third option satisfies the equation. Hence, the third option is correct.