In order to encourage college graduates to start their own businesses, a municipal government has issued relevant policies: coordinated by the government, local enterprises provide products for college graduates to sell independently at cost price, and the difference between cost price and ex-factory price is borne by the government. Li Ming invested and sold a new energy-saving lamp produced in this city according to relevant policies. It is understood that the cost price of this energy-saving lamp is RMB per lamp and the ex-factory price is RMB per lamp. The relationship between monthly sales volume (pieces) and sales unit price (yuan) approximately satisfies a linear function:

In the first month of Li Ming's business, the sales unit price was set at RMB, so what is the total price difference that the government will bear for him this month?

Suppose Li Ming's profit is (yuan). When the sales unit price is set at how much yuan, what is the maximum profit he can get every month?

According to the price department, the unit price of this energy-saving lamp should not be higher than RMB. If Li Ming wants to make a monthly profit of not less than RMB, what is the minimum price difference that the government will bear for him?

This is analysis/exercise/math /268028/? Zjr must be adopted if it is satisfied.