Kensin and Sophia want to build a greenhouse. They are using redwood framing and polypropylene sheets, both measured in the same units (square feet). For light, they want the number of units of polypropylene sheets to be at least five times the number of units of wood. For stability, they want at least 50 units of wood. But the total number of units for both the redwood framing and the polypropylene must be less than 480 to stay within their budget.

Choose appropriate variables and write constraints for this problem.