Prabhat wants to invest the total amount of Rs 15,000 in saving...

Prabhat wants to invest the total amount of $Rs 15,000$ in saving certificates and national saving bonds. According to rules, he has to invest at least $Rs 2000$ in saving certificates and $Rs 2500$ in national saving bonds. The interest rate is $8 \%$ on saving certificate and $10 \%$ on national saving bonds per annum. He invest $Rs$ x in saving certificate and $Rs$ y in national saving bonds. Then the objective function for this problem is