Sushant invests Rs. 12000 in simple interest at the rate of 15% per annum for x years and Riya invests Rs. 8000 in simple interest at the rate of y% per annum for 9 years. The interest amount earned by Riya is equal to the interest received by Sushant. If the difference between the value of x and y is 12. If Vishal invested Rs. 5600 in simple interest at the rate of y% per annum for 3 years, then find the simple interest earned by Vishal.