Question : Directions: By Interchanging which two signs the equation will be correct?
6 – 10 × 8 ÷ 5 + 7 = 15

Option 1: + and –

Option 2: ÷ and –

Option 3: + and ÷

Option 4: × and ÷

Correct Answer: + and –

Solution : Given:
6 – 10 × 8 ÷ 5 + 7 = 15

Let's check the given options –
First option: + and –
On interchanging the mathematical signs, we get –
6 + 10 × 8 ÷ 5 – 7 = 15
Solving the L.H.S. of the given equation –
= 6 + 10 × 8 ÷ 5 – 7
= 6 + 16 – 7
= 22 – 7
= 15 = R.H.S.
Second option: ÷ and –
On interchanging the mathematical signs, we get –
6 ÷ 10 × 8 – 5 + 7 = 15
Solving the L.H.S. of the given equation –
= 6 ÷ 10 × 8 – 5 + 7
= 4.8 – 5 + 7
= 11.8 – 5
= 6.8 ≠ 15
Third option: + and ÷
On interchanging the mathematical signs, we get –
6 – 10 × 8 + 5 ÷ 7 = 15
Solving the L.H.S. of the given equation –
= 6 – 10 × 8 + 5 ÷ 7
= 6 – 10 × 8 + 0.71
= 6 – 80 + 0.71
= 6.71 – 80
= –73.29 ≠ 15
Fourth option: × and ÷
On interchanging the mathematical signs, we get –
6 – 10 ÷ 8 × 5 + 7 = 15
Solving the L.H.S. of the given equation –
= 6 – 10 ÷ 8 × 5 + 7
= 6 – 6.25 + 7
= 13 – 6.25
= 6.75 ≠ 15

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