Let's assume
x be the number of loads by land carriers
y be the number of loads by air carriers
so, maximum number of loads can be 150
total number of loads =(the number of loads by land carriers)+(the number of loads by air carriers)
so, we get

the mail is sent via ground in air each land carrier takes 2000 pieces per load
so, total number of pieces by land =2000x
each air carrier takes 1500 pieces per load the
so, total number of pieces by air =1500y
total number of pieces = (total number of pieces by land)+(total number of pieces by air)
now, we can plug values
total number of pieces =2000x+1500y
A mail distribution center processes as many as 175000 pieces of mail each day
so, we get

so, we get system of inequality as

................Answer