An agricultural operation of 120 hectares (ha) can use three cropping systems noted 1, 2 and 3 to which it must devote a certain surface (in ha). These cultivation systems require respectively 10 hours, 40 hours and 30 hours of work per hectare. The number of available labor hours is equal to 1500. The profit margins per hectare for each of the cropping systems are $ 2, $ 1 and $ 3, respectively. Write the corresponding linear program.