A sum was put a simple interest at a certain rate for 2 years. Had it been put at 4% higher rate, it would have fetched Rs. 60 more. The sum is:

Rs.750

Rs.700

Rs.820

Rs.940

Explanation:

Let the sub be Rs.x and the initial rate be R%.Then

$\dfrac{\text{x}\times (\text{R+4}) \times 2}{100} - \dfrac{\text{x}\times \text{R} \times 2}{100} = 60$

$\Rightarrow \dfrac{\text{x}\times 4 \times 2}{100} = 60$

$\Rightarrow \dfrac{\text{x} \times 2}{100} = 15$

$\Rightarrow 2x = 1500$

$\Rightarrow x = 750$