Amail distribution center processes as many as 150,000 peices of mail each day. the mail is sent via ground and air. each land carrier takes 1800 peices per load and each air carrier takes 1500 per load. the loading equipment is able to handle as 150 loads per day. let x be the number of loads by air carriers. which system of inequalities represents the system?
a: 1800x + 1500y ≥ 150,000 x+y ≥ 150
b: 1800x + 1500y ≤ 150,000 x+y ≤ 150
c: 1500x + 1800y ≤ 150,000 x+y ≤ 150
d: 1500x + 1800y ≥ 150,000 x+y ≥ 150