Answer:
150 short-sleeved shirts and 100 long-sleeved shirts.
Step-by-step explanation:
We will use elimination to solve this system of equations. We will make the coefficients of x the same in order to eliminate them; to do this, we must multiply the bottom equation by 15 (1/3 of 15 is 5, so 15(1/3) = 5):

Subtract the second equation from the first one:

Divide both sides by 2.5:
2.5y/2.5 = 250/2.5
y = 100
Substitute 100 in for y in the first equation:
5x+10(100) = 1750
5x+1000 = 1750
Subtract 1000 from both sides:
5x+1000 - 1000 = 1750 - 1000
5x = 750
Divide both sides by 5:
5x/5 = 750/5
x = 150