Question : Directions: Which two signs should be interchanged to make the given equation correct?
25 – 5 × 50 ÷ 10 + 35 = 155

Option 1: × and ÷

Option 2: × and +

Option 3: × and –

Option 4: + and –

Correct Answer: × and –

Solution : Given:
25 – 5 × 50 ÷ 10 + 35 = 155

Replace the given symbols in the options one by one with the original symbols in the given equation.
Let's check the options –
First options: × and ÷
On interchanging the mathematical signs, we get –
25 – 5 ÷ 50 × 10 + 35 = 155
On solving the L.H.S. of the given equation –
= 25 – 5 ÷ 50 × 10 + 35
= 25 – 0.1 × 10 + 35
= 25 – 1 + 35
= 59 ≠ 155
Second option: × and +
On interchanging the mathematical signs, we get –
25 – 5 + 50 ÷ 10 × 35 = 155
On solving the L.H.S. of the given equation –
= 25 – 5 + 50 ÷ 10 × 35
= 25 – 5 + 5 × 35
= 25 – 5 + 175
= 195 ≠ 155
Third option: × and –
On interchanging the mathematical signs, we get –
25 × 5 – 50 ÷ 10 + 35 = 155
On solving the L.H.S. of the given equation –
= 25 × 5 – 50 ÷ 10 + 35
= 25 × 5 – 5 + 35
= 125 – 5 + 35
= 155
Fourth option: + and –
On interchanging the mathematical signs, we get –
25 + 5 × 50 ÷ 10 – 35 = 155
On solving the L.H.S. of the given equation –
= 25 + 5 × 50 ÷ 10 – 35
= 25 + 5 × 5 – 35
= 25 + 25 – 35
= 15 ≠ 155

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