Patel brothers have 50 acres of farmland on the banks of River Ganges. They plan to grow tomatoes and onions. Since onions requires less water, the irrigation authority wants the brothers to cultivate at least 25 acres of land with onions. Brothers work in their farm themselves to reduce the cost of plantation. Besides, the government provides the seeds and other farming equipment for free. Even then, they need R500 per acre to plant tomatoes and R800 per acre to plant onions. The brothers have R30,000 now. They earn a profit of R6,000 from an acre of tomatoes and R4,000 from an acre of onions. The brothers want to know how many acres of land is to be planted with tomatoes (x₁) and onions (x₂) to maximize their revenue.