Consider that 'x' is the number of loads by land carrier, and 'y' is the number of loads by air carrier.
Given that each land carrier takes 2000 pieces per load, the total number of pieces processed in 'x' loads is,
Similarly the total number of mail pieces processed by air carrier in 'y' loads, will be,
Given that the total number of mails processed each day is at most 175000,
Also there is an upper constraint of 150 on the total number of loads,
Thus, the given situation can be characterized by following inequations,