Algebra-1

A farmer has a rectangular field with a length of 60 meters and a width of 40 meters. He wants to plant two types of crops, A and B, in the field. Crop A requires at least 10 square meters per plant, and crop B requires at least 15 square meters per plant. Let  be the number of plants of crop A and  be the number of plants of crop B. And the total number of plants does not exceed 180. Write the system of inequalities that represents the constraints for the number of plants.  __________.