Algebra-1

A school is planning a field trip and needs to rent buses and vans. Each bus can hold 40 students, and each van can hold 10 students. The school needs to transport at least 120 students and has a budget of 1,000 dollars. Buses cost 200 dollars each, and vans cost 100 dollars each. Let  be the number of buses and  be the number of vans ( are non-negative integers). Write the system of inequalities that represents this situation. ________.