Please help to solve this

3. A corn farm can be harvested once every month. In a month, up to 2,500 corns can be harvested in which it can be sold at RM 0.40 per corn. If the harvest is delayed up to two months, the cost price will go down as low as RM 0.10 per corn but the crop will increased by extra 2,400 corns per month. In addition, the amount of spoilage is approximated to be 200 corns per month for each month he delays harvesting. Estimate the time he should harvest his crop to achieve the maximum net cash return and the amount of the crop he will received at that time