Algebra-1

A school is organizing a field trip and needs to rent buses and vans. Each bus can carry 50 students, and each van can carry 10 students. The school must transport at least 200 students and has a budget of 1500 dollars. Renting a bus costs 200 dollars, and renting a van costs 100 dollars. Let b be the number of buses and v be the number of vans (b, v are non-negative integers). Write the system of inequalities that represents this situation. _________.